Well, now, some people do care about these things. You aren't taking MY time commitment seriously if having Skill Focus: Diplomacy instead of leather armor proficiency is an issue. I gain pleasure from having a character with fluffy feats. My time playing D&D is wasted without it.
This is a playstyle difference here is all. Some people like playing "optimized" some people kinda hate feeling pressured to. I think 4e does a good job in supporting both styles. It's why it's important to play with people who have similar tastes.
Skill Focus: Diplomacy is a completely valid choice. When did I say otherwise? The ability to make nice with the locals, defuse potential combat situations, gather additional resources from those in power... Completely valid optimization approach. As I made clear, optimization is about teamwork. That selection fits an incredibly important role.
And, as I wrote, optimize away RPing at the table and at home in your journals. I love reading 'em. I'm not taking any of that away from you by asking that you pull your weight as a team member in both the tactical and the interactive phases of the game.
I've played one session of 4e thus far and already I can see that teamwork is incredibly important in this edition. If someone's busy taking feats that make them feel grand or choosing builds without an eye towards party survivability, well, that puts the entire party at risk... That's not really teamwork in my book. If everyone's on board with your play style, though, go to town and have fun. That's teamwork of a different sort. See my sig before you go the gizmo33's route.
But, if you don't have everyone on board, consider that having a good mechanical character is good role playing when you consider that most adventurers would choose to get better at things that would keep them alive in their primary occupation: adventuring.
Edit: I think the difference, from my perspective, is that optimized choices will never make me responsible for your character's death while non-optimized choices might. I don't want to spoil your fun, so I optimize. Your character isn't going to die by taking a more mechanically sound build. That's my point.