My thoughts;
When I try to role-play a character, come up with a detailed backstory, attempt to interact with NPCs, I inevitably seem to be wasting the rest of the players times, and neither of my regular DMs have any interest at all in my character background. They've written an adventure, my task is to go through it.
When I write up something that I find interesting, but turns out to be less-than-optimal, I *always* end up frustrated, and particularly so if the rest of the party has to waste resources covering up my character's inadequacies. (An Arcana Unearthed tournament con game I played as an Akashic comes to mind. Every other party member had to use a minimum of two healing 'potions' or spells on the useless peice of crap, and she managed to inflict a total of 4 hp of damage in the entire combat. A skill-centric character, in a game that required a single skill roll, which the party Magister rolled better on anyway. It's not juts that *I* didn't have fun, it's that my character ended up being a hindrance to the rest of the party, and detracted from *their* gameplay.)
So, in the interests of
a) not boring my fellow players,
b) not annoying my DM, and
c) not being frustrated and not having any fun personally, I write up my two page backstory, toss it at the back of my character and ignore it, just playing something effective. I regularly end up hopping around between a half-dozen books, finding feats, skill synergies, spells, alternate class features, etc. that fit my theme.
And yes, 'best damn archer in all of Middle-Earth' *is* a theme, as is 'unstoppable dwarven tank,' or 'Johnny one-spell magic missile specialist.' Just because Clint Eastwoods character in Unforgiven is the best damn gunman around, does *not* mean that the writer was a two-dimensional immature power-gamer.
Optimization has obvious rewards, but it also has it's downsides. It's all-too-easy to stomp on an optimized character, as many of them are highly specialized and require certain pre-conditions to function. The DM can easily control these factors, for whatever scenes he wishes to limit their potential. He's the one with the remote, after all.
I'm all for role-playing, and I've happily played LARPs where I didn't get any experience at all, since the play was the fun thing, not the advancement. (In fact, being such an optimizer, in games other than D&D, such as GURPS or Aberrant or Mutants & Masterminds, my character is often 'done' at character generation, and I have no idea what to do with earned exp anyway, since everything I wanted is already on the sheet...)
But for d20, gaining levels is the name of the game, and so I'm gonna make characters that are not only good at that, but also aren't holding the rest of my friends back in their quest to do the same. My fun is not more important to me than their fun, so I'll crunch the numbers, roll the dice and save the role-playing for writing up a neat-o backstory that nobody but me is gonna read anyway.