The main problems with this game revolve around issues with balance and the skill gap, and both causing people to desert the game. Veterans hate the changes, new players hate getting steamrolled. Here's what should have been done;
Remove Maximum TDM and FFA and replace them with Classic C2 rules. Nobody plays those modes at all (literally on 360) and as it's a less forgiving set of rules, would still serve as a hardcoe mode.
This would satisfy the veterans who hate things such as AA, poles, pingers and alien weapons, it would keep them away from the core modes which would stop new players getting wrecked and give them time to develop skills, and everyone in theory would be happy.
Why do we have modes such as Medley, Max FFA, Max TDM and Developer's Choice, that people neither want nor play? As it contains the exact same bugs (including lazy crap that should have been fixed like the HMG glitch) it's clearly the exact same engine at its core as C2, so could easily have incorporated the original gameplay code.
We should have 3 tabbed categories;
Core; (C3 modes)
FFA
TDM
Mercenary TDM (no more squads)
Crash/Spears
Extraction/Relay
Tactical; (non-nanosuit and pre-set nanosuit loadout modes, using C3 rules)
Hunter
Assault
Cell Vs Rebel
Classic; (C2 EN balanced modes, but using C3 guns, maps, killstreaks and modules)
FFA
TDM
Crash Site/Spears
...in this mode there would be no poles/shields/pingers/alien weps - max nanosuit would also be reduced to C2 levels. AA would be disabled and replaced with Air Stomp as a module, with integrated Air Stomps taken out to better mimic the C2 suit. Melee would also return to a 2-hit. Cars would kill allies, etc.
That, to my mind, would have solved all the problems as far as I can tell. You could even have made AA compulsory in the core modes as originally intended that way. I'm sure this could still be accomplised via a big old patch too, but as nobody plays the game I understand the expense would be completely unjustifiable, which is a shame.