Probably the biggest innovation in the last 15 years has been in the terrain we now ride. I was thinking as I rode up a hugely horrible climb on my 32lb 6" travel AM full suss last week that even when I was the Scottish MTB champion I could not ride my 24lb hardtail up this bas&*rd; and yet I'm less fit now but I made it to the top with a heavier bike and no dabs (yes, I could have walked it but I ain't no soft southern jessie, if it can be ridden it has to be).
I didn't have much time to think about the same on the descent but back in the day it really was a struggle on the race hardtail with many sections that needed walking... once again the big bike worked it's magic and the descent while still difficult was brilliant and I rode it all.
Oh how we laughed at Proflex and the other first suspension bikes... it will never catch on... disc brakes are heavy and you don't need all that power... SPD's will never replace clips and straps... thumbshifters are the best... elastomers are all you need for suspension... 2" inch travel is enough for world cup DH... you don't need a bigger tyre than 1.9".
We still have a load of roady orientated out of date bits and pieces that could do with some innovation. I snapped a saddle the other day... would not have happened with the I-Beam on my other bike.
HammerSchmidt is awesome - make it lighter please?
I've not gone for a droppy seatpost yet but I probably will soon once they get more reliable (I hate rattles on my bikes).
I'm not for going back and I watch each year for the little things that are real improvements... (although I do enjoy riding my 20 lb rigid singlespeed just as much as my other bikes) It's all bikes and it's all great.