Yep, my own fleets retreat regularly. Running away is better than taking out a "few more ships" and losing a lvl 5+ capship (or two). Retreating is closer to human tactics than throwing units away, IMHO.
This of course can be true.
But the problem is, the AI is still retreating so often, that it ends up having nothing to defend.

Also, it's no fun. Decisive battles are fun. Large battles to the complete annihilation of the enemy are fun.
Battles where one side retreats after a few seconds are just boring.
If the AI would lose after it had lost a large battle, nice win for me. Yay, fun!

But instead the AI just runs away until it has not enough planets to win. No fun.

Edit: But now it's of course a bit better then before. The sometimes even stands and fights! *shock*

But imho still not often enough. Though it's a step in the right direction.