I totally agree with you!
I've noticed the same thing; it's either rams or elephants, nothing else has the armor and destructive capability to get past the towers, and fortresses of the already too difficult ai.
I think what we should do is put something that makes building champion-normal soldiers more rewarding, and also change the difficulty of the ai for the better. In ancient times when Macedonia wanted to conquer Persia; they didn't build 200 rams and launch them straight for the civic centers.
I think the defense towers and fortresses make sending soldiers into enemy territory too hard, we should weaken the destructive capabilities of those obstacles.