“then again, how many more trees are there in crysis than in GRAW2?“
The BOS line of PPU games had jungles like Crysis with even better tree physics then GRAW 2. You could blow off leaves.
Yet the youtube video you posted shows the frame rate being appauling

There is visible stutter not only noticable when he moves around but when he is looking at the trees
And regarding the change the ini comments, why?
If the current physics are satisfactory why would you change the radius to something un-needed?
Your version of "high physics" arent high physics at all its the same physics being done on a larger scale which is not needed in the game as it will make little/no difference to the player playing
IF your point is that dedicated PPU hardware, on board a gfx card/cpu is needed for very high levels of physics i 100% agree with you, i would love to see PPU's on a gfx card and developers using them.
HOWEVER regarding the specific example of crysis the ini tweaks are not needed as the ones in there atm are more than sufficient for the majority of users
If on the other hand your point is that the current PhysX offering is wanted or needed then i have to disagree, it is too expensive for what it is and it is not worth the price aegia is asking.
Unfortunately PPU's will never take off until big names like Ati and Nvidia start implementing them into their hardware, the fact they havent shows how small the market is for them