I am using 5870's atm, so if anything, I should be agreeing with you, but you seem to be imposing your opinion on others. I know mousemonkey, for example, has at least half of all the GPU accelerated PhysX games, so I would imagine someone like him, would want to have physX. It also might be that he went out of his way to take advantage of physX when choosing games, which probably would give him more incentive to get physX.
I have a dedicated 8800gts for physX myself. It's not game changing to me, but it is nice to have.