I dunno, affordances are pretty nifty. (http://en.wikipedia.org/wiki/Affordance) It's a tradeoff of clutter vs. learning curve. And I have to imagine the future will, as always, be a tradeoff between the two.
Its a great point and I love a good set of affordances, that said all it took was seeing the 4 finger gestures on the ipad once and I could never forget them. The 4 finger pull the a up for switching and full hand movement for closing the app are so natural.
OsX has gotten rid of the little handles on the edge too- I imagine its all going to disappear.
