infinity blade was legit awesome and made fantastic use of the swipe control scheme. the gameloft stuff was pretty good too, but modeled off of console/PC games of course. its sad that it all became tower defense, because there were some cool innovations for a bit.
there are still good games coming out on mobile, you just have to look even harder for them now. i would say "innovation" in mobile actually happens more often than in the AAA sphere because they go through trends so fast.
tho in the end the problem with graphically "high end" mobile games is that they take up lots of space and battery. most people don't use their phone primarily for gamming. for instance infinity blade was really fun but it sucked having to delete 10 music albums just to install and it was unfeasible to play it for a longer time without access to a power source.