I think those are all good settings for the music. For each era, you could even create an intense piece, and a relaxed piece. For thinking of other settings to create music for, the easiest is settings that can be easily defined, such as technological level (tribal, antiquity, medieval, etc.) or climate (desert, jungle, upper atmosphere). Things like nationalities, traditions, or social structures (even something like “communist” music) are much harder to define.
I agree with @NickTheNick - those are good thematic targets to aim for. You don’t need to make loads, though, since these won’t need to be included in the game for a while yet. You can differentiate them into different nationalities or cultures, but we’ll need generic stage music too without those divisions.
Also, if you’re interested, I’m working on updating the Main Theme, and I’m looking for other people to contribute ideas or music to add in. It’s by no means a priority and you don’t have to, but if you want it’d be great to get as many people’s input as possible.