I'd like invasion to be its own sweet little thing. Massive, aggressive and strictly objective oriented to oblige cooperation betweeen all team players. "Cinematic" moments would compliment players for their difficult but necessary cooperation.
I don't care if they lift geometry or get their homeworks done by their big brothers.
I just consider offering lots of maps as a conciliatory move, like saying they can't all be good so, here, have some choice.
I want good maps, not good intentions.
One thing (not sure if it was the community, or Bungie) that I'm sad to not see pan out was carved out versions of the Invasion maps being used for other playlists. I know a few people on GAF, HBO, etc have made these, but either the work on them peters out or nobody wants to test them.
I'm still disappointed that Headlong didn't have official support for Invasion, since having access to be able to actually do animations and stuff would have added a pretty nice layer of immersion.
It'd make my day to see something like an Invasion Map Pack, since Breakpoint shows that a map made specifically for Invasion (with the rest of the game as a known factor) can be an awesome experience. I'd also expect that map pack to be set up for carve outs for other playlists. It'd probably would help if Invasion could have a Slayer phase.
Interestingly a problem with the Invasion maps in BTB is all the dead and unused space which is only really used in the Invasion gametype. I say interesting since Halo 2 was supposed to have Invasion, and so was 3, and Last Resort has a bunch of dead area on the beach and Sandtrap has a bunch of dead area as well in normal gameplay. Both were Invasion maps. Perhaps any Invasion maps should have big Forge buildings (not basic shapes, but actual buildings) that they can place for normal gameplay to make that part of the map interesting.
What it kind of boils down to is that Invasion is an Asymmetric Map on Steroids, where the developers and the community want maps more capable of supporting most other gametypes. The problem comes from trying to play symmetric modes on them. You wouldn't try to play 2 Flag on Zanzibar or High Ground, so gametypes like Stockpile on Spire are just headscratchers. It also doesn't help that some of the 1 Flag and 1 Bomb setups are just weird (Spire would seem to make more sense on the first phase area instead of that weird sideways setup in the second phase, and Breakpoint's setup is just wtf for 1 Flag and Bomb, and let's not even talk about Boneyard's 1 Flag/1 Bomb setup).
tl;dr Make Invasion map, then do a Certain Affinity and make extensive Forge capabilities to turn it into a normal BTB map (blocking away dead areas, etc)