Incorporating Air ships, transports, and potentially bombers would make a great addition. I remember in SWBF1 that I enjoyed just taking troops to and from spawnpoints in the transport on Geonosis. For example, the Bespin map. I loved with a passion being able to fly a ship around and shoot at soldiers on the ground. Side note, adding buildings for cover and height depth would be great. Having skyscrapers everywhere around you, or even just 2 story buildings in a town-square or something. Balconies and small little cubbies do not count as buildings.
Personally though, I think that vehicles should be put into more use. They have a whole range of vehicles, yet the map only allows 1 to 2 routes of possible value, unless you plan on crashing through trees/pillars of rock. Other than the droid speeder, all other speeders kind of limited navigation by only going straight, as turning became quite a challenge. Maybe an all-terrain vehicle is needed. For Star Wars: Empire At War: Forces of Corruption fans, what about that Imperial Transport Rover? Fully armed with anti-missile systems, it can carry a significant amount of people across any field.
Also, adding more than 16 players at a time would be nice. I'd say 25 AI through 39 AI would be a great play-time. And on that topic, there should be interactive environments. Though that would reduce alot of other visuals, it would still add to the effect to see your tank's blasters be shot off, or a bridge for bigger vehicles/ troop squads being destroyed.
On top of that, more than one jedi/sith would be nice as well. Having only a player as the Jedi (SWBF2) was kind of an overkill, and either totally ruined the other team, or died faster than you can do anything with. Having 2 AI force users around (SWBF1) was better, personally, but I still would want to see Vader choke someone and/or throw someone off the edge.
Yeah, that's only a fraction of an opinion I have.