I'm trying to ask enworld posters if they think the very idea of there being specific things you need to do to make a "good character" is something mechanically required due to the game by design, or if it is entirely originating from the community.
Yes to the first and no to the second.
One part is simple game theory. Given two choices where one choice leads to better results than the other, a game player will gravitate toward the choice that's more beneficial.
These days, we call this optimization. It's really just part of any game and game design.
Designers know this. The balance of the game is wrapped around it. There is nothing in the system stopping a player from playing a fighter with 8 strength wielding a kukri he is not proficient with (sorry it's hard not to get into specifics, but examples make life easier). It is assumed you won't do this, because you are playing a game and (theoretically) want a functional character. The more "functional" a character is, the more "optimized" we say they are, but really, it's just looking at the choices, and picking the ones that provide you with the best tactical options.
Introducing community into game design, things start to get fuzzy between people who have a predetermined expectation of what they want to play, and try to realize that image, and people who simply examine their options and choose something to play from those options. The former group is often more adamant about not caring for rules benefits, if it means they can play a shapechanging warden who doesn't wear armor on his tattoo covered body and uses a pair of tomahawks. The latter group is more impressed by how they can build a defender who can take fifty bullets from an Uzi and not go down.
So I believe it's actually community that drives the game *away* from optimization. The books give us the mechanics. If we're playing a game (with no foreknowledge of community preferences), we will build characters who make "good" game choices. As it stands, there is a lot of history behind roleplaying games, and for lack of a better phrase, "gamer pressure" that tells us we should play a concept, and shouldn't play the rule system.
In conclusion, the system asks for and expects optimization because it is a game. Part of the community responds favorably to that demand (we call them many things, "optimizers", "min-maxers", "power gamers", etc). Part of the community cries out in pain (we call them many things, "hard core roleplayer", "old school", "grognard", etc). And another part finds a mid-point where they can continue to enjoy the experience with the tools that are given to us (I'll call them "players").