Why is it considered good design to have all ability score adjustments an even number

[Beholder Bob]

A +/-1 mod simply skews up the race slightly. A player can shove the mods on an odd score to try to hide the effect - but as was pointed out, dump stats are used the same way. Random stat generation is fairly resistant to too much abuse with this system, though point buys are susceptible to it - and more prone to the efforts of munchkins to begin with.
The 'not noticing' the impact of -1 STR poison example is silly and as counterpoint - the 17 STR fellow finally got the advantage he deserves, he is, after all, stronger then the 'puny' 16 STR guy.
The odd value allows for good race development - and the comment about it making it race power difficult to gage, well a +1 is 1/2 as potent as +2. The +X magic items coming in odd values work fine - gauntlets of +3 STR helps anyone, though the guy with the 17 STR gains a higher benefit then his 16 STR friend - but he IS stronger to begin with.
If you fear folks may slip through the cracks, drop stats in 1/2 so each point is worth something! With initial STR of 1-9, it makes calculating the bonuses easy.

BB

 

[irdeggman]

Bottom line is that this was one of the design criteria for 3.0 (and 3.5) so it is inherent in all aspects of the mechanics of the game.

To randomly attempt to change this is just asking for trouble in the long run. Every time I (or my DM) has tried to make slight adjustments to the RAW we ended up having to make a series of other changes just to keep things balanced.

 

[Ankh-Morpork Guard]

Think of it from another view...you and someone else in your group are both playing Elves.

Because of how your stats work out, your +1/-1 Dex/Con ends up only hurting your Con score and not helping your Dex. But your friend gets the opposite, essentially making him a 'better Elf' than you even though you're the same race. Its cheesy to say, but situations like this would pop up all the time and its simply not fair to PCs.

 

[Lamoni]

I have a slightly different, but related question. What is the benefit to having abilities of 10-11 = +0, 12-13 = +1, etc. What would be the problem of doing away with the score and just using the modifier as the score? So a PC could have stats of 3,1,1,0,-2,4. Things that decrease stats by 1 currently could just do so half as often, or have an easier saving throw, etc. Death or disability could still occur when stats reached -5. Is there any inherit advantage to using the current system? Just using the modifiers as stats seems like it would be a lot simpler. I don't think the math is too hard like it is, it just seems unnecessary.

 

[bmcdaniel]

And equally noteworthy, odd modifiers let you improve strengths and hide weaknesses.

For instance, if you have

Dex 13
Con 13

and if Elves got +1 Dex and -1 Con, then you could get

Dex 14
Con 12

Which improves you Dexterity modifier, but doesn't hurt your Constitution modifier, basically negating the 'penalty' to your Con score.

But, by the same token, odd modifiers also prevent you from improving strengths and disguising weaknesses.

For instance, if you have

Dex 14
Con 14

and if my Alt.Elves got +1 Dex and -1 Con, then you could get

Dex 15
Con 13

For a net decrease.

But, you might reasonably interject, no rational min-maxer ("RMM" for short) with those ability scores will choose to be an Alt.Elf because of the bad impact on ability scores. This is a fair enough objection, but:

1. RMMs already choose to optimize their race in way that maximizes strengths and minimizes weaknesses. For example, no RMM will select a standard elf when he has a Dex of 10. Why? a +2 bonus to a 10 stat isn't as valuable as a +2 bonus to a 14 stat.

2. More important, under point-buy scenarios, ability scores are not determined prior to race and class. They are all determined together.

Using the standard DMG point buy, for an elf to get a +4 dex modifier (ie a 16) costs 6 points (ie a 14). For the alt.elf, to get the same dex modifier costs 8 points.

Indeed (again, ignoring the every 4th level increase and feat repreqs) no RMM will ever use point buy to buy an odd ability score, except at the end of the process to allocate any left over points.

 

[Nail]

It is unnecessary......after you've generated the ability scores in the first place. Remember 3d6?

Having your ability scores vary between 3 and 18 (before racial modes, etc) is fun, it produces a nice bell curve, and it's a legacy of the D&D system. Why change it?

 

[Nail]

Using the standard DMG point buy, for an elf to get a +4 dex modifier (ie a 16) costs 6 points (ie a 14). For the alt.elf, to get the same dex modifier costs 8 points.

An excellent point. Sure, you can hide the penalties....but you also have to pay more for the benefits.

FWIW, the humans IMC get a +1/-1 ability score adjustment during PC generation. They are the only race that has this. The idea is to model the human's adaptability.

 

[bmcdaniel]

Let me make the point with an example. Suppose I am creating a new character with a 25 point buy, weighted per the DMG. I can choose between a human (no ability score modifierd), elf (+2 Dex, -2 Con), and a nonstandard half-elf (+1 Dex, -1 Con).

Suppose I am aiming for an archer-type, and I want at least a +3 Dex modifier, and a +0 Con modifier. Prior to applying the racial adjustments, for each race I need the following:

Ability Scores
          Dex   Con
Human     16    10
Elf       14    12
Half-Elf  15    11

Point Cost
          Dex   Con  Sum
Human      9     1    10
Elf        5     3     8
Half-Elf   7     2     9

Assuming that the player ultimately wants a higher Dex than Con (and if not, why choose these races?), it will always cost less in a point buy system to be an elf than this modified half-elf.

So, if you disagree with me, please show me how this alternate half-elf is abusive, compared with the elf or human under a point buy system.