Here are some ideas in no particular order... I tried to refrain from 'nerf this or that' type arguments.

I liked the idea posted elsewhere - newer / more variety in planetary maps ( forest, jungle, water, cities, complexes, etc ) would make things really interesting. Dividing a battle field with a river or gorge would add a new dynamic - imaging having to use dropships, or otherwise having to use a hotly contested choke point like a bridge to get to an objective.

implement 'climb' option on more surfaces than just a ladder. I should be able to climb onto a tank, or a cliff face, or if we ever have trees and such, I should be able to climb those.

Dropsuit Armor and vehicle skin customization would be fun - other games do it. Would be nice to put a personal touch on our characters. Corps could have uniforms - lone wolfs could design their own sigils.

More vehicle diversity.

Destructible environments. It is maddening when an infantry guy can hide from a rail turret simply by ducking behind a railing. It would be sooo much fun to see stuff get blown to bits and would change the dynamics of battle dramatically. People wouldn't be able to hide behind that wall anymore, b/c the wall itself was reduced to rubble. No more crossing that bridge.. it was blown up.

Taunt or dance animation just because people want to rub your nose in it ( plus you could make some pretty funny videos for you tube ). Imagine a scout doing some Michael Jackson moves, or a Heavy doing the robot.

Retrieve equipment ( nanohives / uplinks ) similar to recalling a vehicle

Hack equipment ( nanohives / uplinks ) similar to hacking vehicle

Portable vehicle resupply hives.

Portable shield generators - similar to nanohives - drop it to create cover.

Jet packs for short flight ( susceptible to AV when mobile ).

Proximity mines for infantry.

Change 'red line' dynamics - yes I understand the red line exists so people can't camp the spawn points, but you shouldn't be permitted to engage from behind them either. Set the 'safe' spawn point and the red line further back and those that want to use it need to take longer to get to battle. Prevent being able to fire from behind them, like you did with the MCC. I believe when I first started snipers used to hide inside them and fire from the loading bay, but that doesn't happen anymore b/c some kind of shield prevents you from doing it. You could implement the same effect with the red lines. Either that or simply increase the redline death timer to maybe 30 seconds and make it death to everyone - no matter what side you are on - to force people out of them.

Allow MCCs to take damage from other sources ( like installations, vehicles, and even AV if close enough ).

Change the bounding barriers on existing structures to be more forgiving. There are some towers that actually have balconies at the very top. Would be awesome if we could actually walk around in those.

anyway.. just some thoughts.