Maxperson
Morkus from Orkus
The characters are aware of the in-game reality which the rules reflect, and given that I won't make a character who is suicidally incompetent, there is no conflict between Optimization and Role-Playing. A character who chooses a sub-optimal weapon, merely because it is "cool", is a fool and a liability that shall not be suffered by the other individuals in the group.
Hey, you're right. In the real world long swords do more damage than short swords, so therefore short swords don't exist because only a fool would use one. Right? Or maybe there's more to deciding what to use than mere numbers dealing with damage.
Seriously, building an incompetent character is a jerk move to everyone else at the table. Don't do that. If you fail to kill the dragon because your sword only does a d6 instead of a d8, and then the dragon breathes fire and kills the whole party, then that TPK is entirely your fault and you should feel bad. There are millions of ways to build and play a character that isn't incompetent; it is not a meaningful limit on your freedom of expression.
Wrong, wrong, wrong. A d6 over a d8 isn't a big deal, and if the party is going to TPK over that trivial amount of damage, there are much bigger issues going on than short sword vs. long sword.
Go ahead and optimize your heart out, but the rest of don't have to play by your "one true way."