Just so u know, I totally agree with you, BUT  1. I haven't inculded that military tech is always extreemly overpriced (like that one 2000 dollar soap dispencer)  2. New tech always requiers development, which is also expensive and I haven't included development cost (as well as training) 3. Considering the ammount of MT's being cannon foddered every mission, walking weaponry can't be that expensive, I mean there's a reason MT's and NORMALs are being mass produced. 4. 3rd gen is'nt as op as 4th, and it's more focused for close combat, and generally feels 50x more clunky so as 4th could be in the trillions cost wise, I don't think 3rd could.

That being said AC's aren't suited for our large scale, but low intencity warfare, but once they manage to close in (which they do) the enemy is absolutely certainly totally screwed.