That was then, now we have game like Batman, and who knows what else they're going to release. You can't compare it... In the 4xxx era, PhysX was mostly just a promise, now we have actual big titles coming out with PhysX support.
Yes i can compare it and im doing it right now. We had UT3, Mirrors Edge and about 7 other titles yet it didnt do much for nvidia sales. Now we have one more game - Batman.
And besides who knows what else DX11 will offer? Thats the same level or argument really.
I tried few of the advertized free physix titles on 8800GT (i dont even remember their names now) and expirience was not really good and performance even worse. Im sure Batman is much better than that (since it seems to be a good game in itself) but its way way way too little to get many sales when new Ati hw will be out. That TGDaily article linked earlier may have bigger impact and give Nv some time to realease DX11 HW IMO.