True, but I also feel this might also be part in staying relevant with touch displays. The dumbification of UI coincided with the rise of tablet computers and touchscreen devices. Windows 8 came out around that time too.
I personally preferred Gnome 2 when Gnome 3 came out, but I've gotten pretty used to the top-left corner flick after a couple weeks. I sometimes do it on Windows and get disappointed when nothing happens :) This sounds somewhat perverse, but I kind of like the fact that it takes a little extra effort to switch applications. I'd say it keeps me maybe 5-10% more productive!
Ideally, UI's should be tailored for the device they get installed on, but I'm happy Gnome was able to accept a few design compromises in order to keep moving the project forward.