That is pretty much the problem of the genre yes, that they keep repeating Age of Empires 1. At first there was still innovation like with Rise of Nations and of course Age of Empires 2, but after that it stayed pretty much the same.
It's silly though since there still is so much room for improvement both visually and gameplay wise.
-army customization.
-ability to put missle troops on walls.
-siege towers, ladders and such. Allowing light castle building elements.
-finishing animations.
-Unit formations such as Phalanx, spear wall and wedge.
-road and bridge building.
-Focusing on city factions or counties instead of nations for a better sense of scale with just having a few hundred people under your command. I really miss commanding a small army instead of a nation.