The Air Vehicles are basicly useless because you cant take over a point with it.
AT-ST? Doesnt take long to get destroyed when the enemy team spams the Ion Torpedo and Grenades.
Rebel Spawns need to be changed.
Hoth suffers from the same issue. The Spawns are really really bad in that mode. And i love Supremacy.
I hope they adress this issues soon.
I do agree about the spawns, they need work but try this ATST strategy on Tattoine: As soon as you can move, push up immediately all the way to at least the small incline just in front of the Sand Crawler on the Imperial side. The Crawler is really tall and fairly wide so it blocks any long distance lock ons except from Rebels who have well and truly flanked on either the left and right of the Crawler.
You'll have to worry about Rebel air forces just pounding you until you're dead as usual, and I hope the ATST does get a slight health buff, but the crucial moment is the first few minutes of the match when the central capture point next to the Crawler is being contested and that's usually when the two sides air forces are fighting each other so they won't be worried about you initially.
From your position, you have a perfect line of sight on either side of the Crawlers treads, so it basically works like a trucks rear view mirror: if they can see you, you can definitely see them. So with that perfect view of the capture point, you can strafe from side to side avoiding fire. You will have to keep an eye on your flanks if you get the sense your team aren't very smart, but other than that I think its a good strat on that map playing as Empire to at least try and get your team on the front foot.