As is often the case, I think the gimped characters fallacy is based on conflating two. As another poster notes, flawed characters are more interesting -- it's often what makes them interesting. But, "flaws" in that sense are character traits, grist for role-playing, and don't necessarily need to be mechanically supported or have any relationship to the mechanics. My characters can be reckless, cowardly, shortsighted, physically weak, and so on without needing particular mechanical support for that.
Second, I think the gimped character fallacy is based on a belief that an optimized character is abandoning the character part for the optimization part. This is, of course, brings up the Stormwind Fallacy. There is something to this, however, when "optimization goes wrong" (tm). I think if someone wants to play a twf with a sword and an ax (to borrow another poster's example), that's perfectly fine. The response from the optimization community should not be "don't play that" except under very rare circumstances (e.g., a very high-powered game where such a character would be out of place with the other established PCs). The optimization community's responses should, I contend, be ways to make that character viable at the table, where "viable" means able to succeed in the things the concept wants to. In this case, probably running around and slashing people to bits.
To the extent that optimization, the opposite of gimping, leads people to abandon character concepts/archetypes that are interesting, leading people to always playing Druids or what have you, then the gimped character fallacy has a point. But, in my humble opinion, character optimization is supposed to do the exact opposite: to make mechanically interesting and viable concepts and archetypes that are not obviously supported by the system.
P.S.: I can only speak for myself, but I find ImperatorK's posts here both dismissive and vaguely insulting. If you feel that way, then why post in this thread or even bother having an account on these boards? If it's "just a game" which implies "why do you give a shit?" then why even bother having forums like this ...