Sure, you could leave all that exalted nonsense to the mount collectors and crazies. And at some point in the (probably nearer than you expect) future, players who take longer to push up their rep or start raiding earlier in their relative play curves are likely to start outgearing the valor gear with raid drops before they've even earned the chance to purchase it. If you really detest dailies, you don't have to do them.
Unless, of course, you do.
What if the rest of your raiding guild or team is pushing up their performance by grinding out these tweaks? When everybody else is getting a leg up on you, you're going to fall behind if you don't join in the "fun." Suddenly, those dailies are looking a lot more mandatory, aren't they?
What if the pressure to run dailies is tied less to the demands of the game than the company you keep? If you're feeling pressured to do unwanted dailies, where is that pressure coming from? Are there members of your raiding group who don't have rep gear? Are players without rep gear or full rep gear causing your raid group to be unable to get past the encounters? Have rep rewards become a mandated step on your raid group's raid gearing ladder, or is there an unspoken rule that this is simply how things are done? Is the choice to grind out rep gear more a nod to an internal drive to excel?