I liken PhysX to what I call the "iPhone phenomenon".
How many people have you seen with iPhones who are all too keen to show you their light sabre app or iPint software or any number of other pointless gadgets but, when asked what they have installed on there that's actually useful, can't really come up with anything.
Too damn many in my case and this is the problem with PhysX - all it adds to games are pointless "bells and whistles" which are incidental to the game itself and which the latter could easily live without.
I'll challenge you on that,
I've got useful apps on my iphone that are pretty useful to me.
My Rail, since I'm regularly between cities.
Shazam, because I'm always hearing music that I'd like to know the name of.
Guitar Scales, (i'm learning

) which is useful to have a load in one app on my phone so I don't need to look them up on my PC or have a book with them in.
Guitar Chords, same reasons as above.
Mobile Safari, ok ok, it comes installed, but it's the internet, and very useful to me

.
Seriously though, I get what you mean, I know of people who have iPhones, but don't have a useful use for pretty much all the apps you can get for it.