So I finally beat all 3 Vanilla campaigns on Hard, and I think I now understand why the UEF was losing the Infinite War...
It's because they're idiots.
"Lieutenant, we need you to attack this heavily fortified Aeon base thats just covered in Point Defense and AA. Also her defenses outrange your units."
"Okay, are you giving me something to accommodate that? Field Artillery? Tactical Missiles?"
"No, but if she was stupid, she might have left her power generators on a nearly undefended flank without covering them with shields."
"And what if she wasn't stupid?"
"..."
Or how about
"Captain, you have an incoming Aeon Navy, you need to defend yourself from it. Also watch out for their destroyers, they can mince your frigates and submarines."
"Ok, how about unlocking destroyer tech for me so the fight can be a bit more even?"
"No but we'll give you destroyer tech once you've defended yourself."
"..."
I swear the crux of the UEF campaign until mission 4 or 5 is giving you something useful after it would have already been useful. Still fun though.