I also want to support your idea in another post that PC should get to do cool things sooner. But that is a bigger change than we will see for a long time.Here's the thing: what do you consider a cool thing and how much of your ability to do that cool thing depend on DM fiat?
Ideally I would like to see D&D be broken in to two tiers:
Mundane: lvl 1-10
Legendary: lvl 11-20
Most of the current fighter abilities could be all pushed down into the Mundane tier and then you can get really wild stuff in the Legendary tier. Other classes would be revised to match as well.