You know, it's interesting that we routinely see complaints that a Fighter built to be a melee brute isn't very effective outside melee. The game evolved between 2e and 3e to expand character customization alternatives. This allowed players to focus all of their character resources on "being a melee brute" if desired. Now, a Fighter could be designed with a moderate to high DEX and STR, take Weapon Focus and Weapon Specialization for each of the Greatsword and the Longbow, buy a decent magical bow and greatsword (maybe a +4 equivalent and a +3 equivalent, rather than a +6 equivalent Greatsword and no magic to the bow - 50,000 cost either way) and otherwise split resources between ranged and melee combat, and we would have a fighter who is pretty good at both ranged and melee combat.
But that's not how players think, for some reason. Instead, we design that Fighter to maximize STR at the cost of all other stats, focus all his feats on melee combat and buy the best Greatsword he can get, and to heck with any other weapons. And then we complain that the fighter we designed to be good at nothing but melee isn't good at anything but melee. That's what you chose to build.
The DM has to take part of the blame - if you needed Greater WF and WS, plus all other feats directed to melee, plus the best Greatsword you can get with all your available gold, to be able to hold your own in melee combat, then you're forced to a very focused build. But complaining that my Melee Brute, tweaked to eke out every possible bonus in melee with that Greatsword, isn't good at anything else is disingenuous. It's like specializing my Wizard in Enchantment spells - focusing every feat on making them more effective, specializing in them, seeing out only those spells, memorizing only enchantments, buying magic items that enchant, etc. - and then complaining that my Wizard isn't very good against mindless creatures.
The game can take some blame too, if it is structured to require max'ing out in one area to be effective there, so resources can't be directed to other areas. But if the game were designed around the assumption that putting, say, half the maximum ranks into a class skill would make your character reasonably good in that skill, how many PCs would be petty good in a bunch of skills, and how many would have maximum ranks in half as many skills, being really good at those skills and useless at all others? And then we'd see the push to make the DC's higher, to challenge max'ed out characters, so the more versatile characters become useless, since they can't make those much higher DC's.
Perhaps the model should begin with a look at a member of each class who is a well-rounded representative of such a class - maybe that's a Fighter with a decent AC (say, only hit 25% of the time by a level appropriate opponent), decent melee and ranged attack skills (let's say those enable him to hit a typical opponent 1/3 of the time, and his own AC about 25% of the time), decent damage (a level appropriate threat can be dropped with, say, two average hits) and good hp (it would take about three hits from a level-appropriate opponent, or from himself, to drop him). Let's also say that he's physically fit, agile and can be pretty intimidating or inspiring (so we establish skills that he can succeed with, say, 2/3 of the time against a level appropriate challenge).
I'm picking those benchmarks out of the air, of course, and I think I've made a class that's a bit better at defense than offense. So that's our base chassis, and we build to various levels, with "standard" skill allocations, feat choices, etc. And maybe that becomes our base fighter - with no optional rules, he gets these skills and feats as base class abilities, with no tweaking or fine tuning. This is the "basic fighter".
Now we add choice. Instead of these assigned skill ranks, he can assign his own. He doesn't get these pre-selected feats, he gets to pick all of them (except automatic weapon and armor proficiencies at L1). What happens? I'll bet Marty Minmaxer shows up next week with half as many skills, all maxed out, most (if not all) his feats directed at melee (or ranged) combat (or AC, or some other singular focus, maybe 2 like massive AC and massive melee combat skills), and stats bumped up for the areas he focused on, and dumped for the abilities he dropped. And in a couple of weeks, Marty will be griping whenever challenges would better be solved with ranged combat, or with leadership and interaction (since he dumped CHA and took no ranks in such skills to beef up his melee abilities), or with anything outside the narrow focus of his melee brute. The narrow focus he chose for that character.
Guess what, Marty? You are the author of your own misfortune. No one forced you to dedicate all your resources to be the best melee brute you can be, and suck at everything else. And now, if the other PC's are still balanced, melee combat is a joke, because Marty walks all over it (or the DM beefs the enemy up to challenge Marty, and the rest of the PC's are outclassed) and non-melee challenges become a whinefest for Marty (or get dropped down to a level where he can contribute, so they're a cakewalk for everyone else).
Or maybe the GM looks at Marty's character and says "No way - he's too focused on melee and sucks too much at everything else. Go make a better balanced character." Will Marty say "I see your point, and for the good of a balanced campaign and everyone's enjoyment, I will tone down his melee abilities and beef up his abilities in other areas." and come back with a character which, while still having a melee focus, is maybe 20% better than the typical fighter at melee, and 10% less competent at ranged combat, interaction, etc., so melee is his clear sweet sot, and he shines in comparison to the other PC's, and he can still contribute in other areas, but is clearly not as good as the others? Or will Marty respond "WHAT??? My character is PERFECTLY LEGAL - I made him under the rules EXACTLY AS WRITTEN and I want, no I DEMAND to play THIS CHARACTER". And run roughshod over all melee challenges, gloating over his "system mastery" all the way, then whine and moan throughout all non-melee challenges about how the unfair the DM is, and how much the game sucks in not giving him enough power and versatility, so he's just bored because his PC is useless in these areas?
The more flexibility the game provides, the more onus it places on the players (GM included) to decide what kind of game they want to design and play using the toolbox provided by the game. No iteration of D&D is nearly as flexible as, say, the Hero system or similar "point buy for everything" systems, but 3e was a huge step up from 2e in respect of flexibility, so it increased that onus of the players to find a common level of min/max in their games. I don't think that increased onus was broadly recognized, nor was it highlighted by the rules. But if your 14 STR, 14 DEX, 14 CON, 14 CHA Fighter with a broad selection of ranged combat, melee combat and leadership/intimidation abilities and magic items gets laughed at by a group of min/maxers (with 20 STR, 10 DEX, 6 CHA fighters), or if you're the laughing min/maxer, then you've encountered a difference in the level of optimization and focus perceived as appropriate to design a good character.