But 3e wasn't innovative in terms of RPG's though. It borrowed pretty much wholesale from existing games. Granted the d20 mechanics was pretty innovative, but, otherwise, very little in 3e was unfamiliar to anyone who played games other than D&D. 4e brought in mechanics from other games and put them in D&D, but, again, very little of it was particularly new.
If you only look at D&D, sure, each edition is innovative, but, I'd argue that pulling ten year old mechanics in from other games that have proved tried and true is not how I define innovation.