Or not. I don't think it's unreasonable to assume that the advantages of being big are greater than the advantages of being small in this context. I don't know a lot of dwarfs (in real world terms; little people) who made it as soldiers. Even with guns.
First off, I don't think too many people get involved in a fantasy RPG to play out the real world. Realistic magic does pretty poorly ("Hey, Dragon, watch me pull a rabbit out of my hat!"). Realistically, infection would be a greater concern than combat damage.
The discussion of individuals who deviate from the racial norm vs a specific race which develops tools and techniques based on their own norms would alleviate a lot of equipment issues. How different would a jeep or a tank be designed if humans were 3' 2" on average, or if they typically stood 7 1/2 feet tall?
Wikipedia indicates Pygmies average 4' 11". The Nilotic peoples of Sudan such as the Shilluk and Dinka have been described as some of the tallest in the world. Dinka Ruweng males investigated by Roberts in 1953–54 were on average 1.813 m tall, and Shilluk males averaged 1.826 m. The Nilotic people are characterized as having long legs, narrow bodies and short trunks, an adaptation to hot weather. However, male Dinka and Shilluk refugees measured in 1995 in Southwestern Ethiopia were on average only 1.764 m and 1.726 m tall, respectively. In Tibet, the khampas are known for their great height. Khampa males are on average 180 cm tall (5' 10). Seeing famed warriors in there?
Average heights have increased 4" over the last 100 years (
http://www.scientificamerican.com/article.cfm?id=why-are-we-getting-taller), but I don't believe that has changed much.
Wikipedia also indicates "In the eighteenth and nineteenth centuries, Europeans in North America were far taller than those in Europe and were the tallest in the world. The original indigenous population of Plains Native Americans was also among the tallest populations of the world at the time. Several nations, including many nations in Europe, have now surpassed the US, particularly the Netherlands, and the Scandinavian nations. Now, the average height of White Americans is about the same as for the Europeans they are descended from." So, did the Plains Indians enjoy a huge advantage over the European settlers?
From the same source, "At the extreme end, being excessively tall can cause various medical problems, including cardiovascular problems, because of the increased load on the heart to supply the body with blood, and problems resulting from the increased time it takes the brain to communicate with the extremities. For example, Robert Wadlow, the tallest man known to verifiable history, developed trouble walking as his height increased throughout his life. In many of the pictures of the later portion of his life, Wadlow can be seen gripping something for support. Late in his life, although he died at age 22, he had to wear braces on his legs and walk with a cane; and he died after developing an infection in his legs because he was unable to feel the irritation and cutting caused by his leg braces. " Does that sound like the recipe for a great warrior? Cardio seems pretty crucial to sustained combat.
Enough Wikipedia.
Conversely, Haldamar the 14 Wis 16 Cha barbarian will impress the noble by bragging of his achievements and displaying his martial skill, while Thoofus, the kender who got caught too many times as a thief and is trying to reinvent himself as a performer, is likely to draw scorn and nothing else. What was your point?
I would suggest that, if Thoofus has a 20 CHA and 10 ranks in diplomacy, but you decide he "is likely to draw scorn and nothing else", then you have invalidated the character. He has invested in the ability to be persuasive, and you are simply ignoring those mechanics. If the character is intended and expected to "draw scorn and nothing else", that should be reflected in poor social skills. Similarly, Haldamar has a 16 CHA, which puts him way beyond Graak, the 6 CHA Barbarian (a +5 advantage). That should mean he's much better in social situations than Graak. With no ranks in diplomacy, he still falls way behind Thoofus - his +3 does not compare to Thoofus' +15.
Now, if the question is one directly related to martial prowess, and Haldamar has demonstrated that prowess, I certainly see room for a bonus. Given the bonus for having "the perfect tool" is +2, I would suggest that martial prowess bonus should be limited to the same +2, not +15 so Haldamar overshadows Thoofus. If Haldamar wanted to be really persuasive, he should have also invested ranks in diplomacy. If he also has 10 ranks of diplomacy (meaning 20 skill points - that's not a class skill for Barbarians, and a significant investment), his martial prowess offsets Thoofus' charisma advantage and they're even.
Of course, a better question is why, assuming they are teammates, Thoofus would not be using his persuasive skills to build up Haldamar to maximize the likelihood the team gets the desired answer from the Duke. If they oppose one another, I suspect Thoofus would subtly denigrate Haldamar in the eyes of the Duke, perhaps highlighting the fact that those past accomplishments were by force of Haldamar's arms, not his strategic genius. The fact that (in my more detailed analysis) Thoofus has 10 ranks in diplomacy and a +5 CHA bonus means he's pretty skilled at pushing his agenda over others, and would typically succeed when opposed by a +5 check (16 CHA +2 for perfect tools, but no ranks in diplomacy). Of course, Haldamar might beat Thoofus' roll by 10 (making them even) or more (meaning Thoofus' honeyed words are not sufficient, and Haldamar's warrior reputation wins out), but the mechanics say this is not very likely. Would you provide Haldamar with a +12 diplomacy bonus (making him Thoofus' equal he already got +2 in my example), a higher bonus (so he's better), or a lower bonus (advantage stays with Thoofus) due to his martial prowess?
Looked at another way, with Thoofus having 10 ranks of diplomacy, let's say they're L7. Thoofus probably has a BAB of +5 to Haldamar's +7, and Haldamar likely has a STR advantage. Thoofus is small (probably not a Kender, given that CHA, so I changed the situation there, if nowhere else - why is a CHA penalized race choosing to be a Bard, or a diplomat, again?), so let's give him a Rapier with 1d4 damage, and an overall melee attack bonus of +9 (BAB +5 Size +1 DEX +3 from Weapon Finesse) and no damage bonus, so 1d4. Let's give Haldamar a bonus of + (BAB +7 + 4 STR - 2 Power Attack) and a Greataxe (1d12 + 4 STR + 2 2 handed +2 Power Attack), so he averages 14.5 damage, 12 points more than Thoofus (and gets a second attack). Are you prepared to allow Thoofus to gain a "great combat role playing bonus" to provide him +12 damage, if you are prepared to offer Haldamar a +12 Diplomacy Bonus to push him into equality with Thoofus in his area of expertise? Let's assume Thoofus is studied in anatomy, so he should get this huge damage bonus based on his background, just like Haldamar's martial background is used to support a big diplomacy bonus.
I suspect a +12 damage bonus won't be offered by any GM. For myself, I would suggest Thoofus take some Rogue levels if he wants to get bonus damage for his anatomical knowledge. I would further suggest a willingness to give the martial character a huge diplomacy bonus just for being "a martial character", or for having a high BAB, is an indication of bias towards martial characters - they are getting something for nothing.
How about some but not all? I suspect the list of which is best varies by individual game. I know 3e did present systems for randomly determining what you get when you gain a level somewhere.
Sure, my expectation would be some but not all. Right now, "some but not all" is random rolls to hit and succeed with skills, saves, etc. (and a d20 is pretty swingy in that regard), random rolls for hp (but with higher averages for characters expected to have more hp - we could just give all classes the same dice, maybe d8 for medium characters and d6 for small characters), and a mix between randomly rolled and point purchased stats, with "roll for each stat" being pretty rare (can't remember the last post I've seen where there was no choice) compared to "organize them as you wish". Some, but not all, random character generation. Your comment earlier was that it is, perhaps, time to make it more random, so my question is how much more random, and where. Whatever your answer, I suspect you will have detractors (possibly on both the "less" and "more" random camps).
There's also no reason why they have to be equally viable.
I think this is simply a difference of opinion which we are not going to resolve. The points for structuring the game so characters will be more or less equal at each level have been stated repeatedly already. I am uncertain what the argument against such a structure are. I think most of the arguments have been "it can work either way". So, if it can work either way for some gamers, and for others a balance such that all character options presented in the rules are more or less balanced at each level is important, I suggest that the latter is the best choice. Those desiring balance are satisfied, and those who don't think balance is overly important but can take it or leave it should be OK, since they could take it or leave it. I haven't seen any arguments that "balance is bad" (and if you want less balance, then let's implement all those random rolls, starting with a 1d20 roll, or a broader range, to determine the level your brand new character starts at).
I don't know why he'd be okay with that. If he chose a character with one set of capabilities, and then I reduced them to the point of being unable to act usefully for no reason, I don't see the positive there. What the other characters are or are not doing doesn't really play into it that much.
But you are OK with saying "Thoofus, tough luck for your +15 Diplomacy roll, I'm giving the nod to Haldamar's +3 because HE is a warrior, so that's worth at least a free +17 bonus". Let's compare that to the Blink ability and allow the Rogue to tumble the same distance with a bonus so large it may as well be automatic success, awarded not for character resources invested, but because "he's a nimble roguish acrobat, so of course he can do that". And we'll also let martial characters move the same distance and attract no attacks of opportunity because, after all, they are skilled warriors and know how to move in combat.
I don't see the positive in denying the character the ability to contribute to success in a unique way that is different from the way other characters contribute, but comparable in the value of those contributions. But I don't see why one should have to be a tauric Halfling blink dog to get this benefit. I think a small, dextrous fighter, a Bard, or any other race/class combination (including a half orc barbarian) should have the ability to contribute to success in a unique way that is different from the way other characters contribute, but comparable in value. You are the one who has been arguing that this should not be a design goal, or at least not a priority goal, for the past [how many? scared to look!] pages.
As it is, I not infrequently will end a game with a set of outcomes where one character becomes a deity after having dominated the game and achieved great things, another settles down to a quiet life in the wilderness after having been party to great things, and another is dead after having tried to do great things and failed. The players are fine with that, as long as those journeys feel earned.
I suspect that you do not commence the game with you (and all the players) looking at three fresh young first level characters, and all four of you can point to the one which will clearly dominate the game and achieved great things over the whole campaign, the one who will retire to a quiet life after being a party to the success of the first, and the one who is clearly doomed to die in the attempt. It is the balance between the characters' abilities (racial, class, etc.) which provides (or at least should, in my view, provide) them all an equal opportunity to be the character who ascends, and not the casualty along the way.