Because it should be about time invested. The division between hardcore and casual people is the total amount of life-time it takes them to get rewards--What they can do in a few weeks may take me months, but I shouldn't be cock-blocked from those same rewards... And please don't try and tell me that raiding is harder than any other facet of this game.

And for me personally, as I explained (If you'd taken the time to comprehend it, that is), I can't train a team to get to high ratings because of my committment to my job. That's not something that is flexible when you're in the military, bud.
Raiding is different, to be honest both pve and pvp have their charmes and also a lot of disliking about them, but going on for months on a boss is something different then gaining points in an arena no matter how you put it.

There is no I can't in this world, only I will not.