That's just been my experience. LAN especially seems rock solid, once it's going. All sorts of issues getting it to connect sometimes. Definitely lag sometimes online.
I'm with you on the system requirements bloat. Really sad honestly. That said, I don't think the engine is more 3D than it used to be, is it? I believe it's still isometric 2D with 3D physics. Could definitely (definitively?) be wrong though.
Here's some discussion on it: https://www.reddit.com/r/ageofempires/comments/16aowwc/are_t...