The problem with militairy starbases is that their range is very limited. Once you conquered the surrounding area, the oftenly are no use anymore.

I'd also like to know why Starbases wouldn't be able to travel in space. Theres no gravity - so size and weight should not matter.

Starbases should be able to move - even if its at a slower pace than normal (they can't fight when moving but can defend themselve - how does that sound?)

Here's a possible explination why, a starbase is a gigantic thing, and your moving at FTL speeds. Now it's true that gravity doesn't matter much in space, but inertia still does. the starbase's are so large, that they'd need alot of engines to move, and they all have to be spaced around because of inertia. Every part of the station has it's own inertia, the bases that have parts off them and flying around are even worse. now, what happens when the center of the station suddenly accelerates to FTL speeds, that puts a great strain on the other sections of the station unless they accelerate at the same speed. The forces are probably to great for a station of that size to stay together on it's own, so they're probably gonna fall off compromising the structural integrity of the station, and causing the whole thing to explode. Putting engines evenly spaced might make it work, but the problem with that is the huge energy costs. those starbases are bigger then even the Gigantic ship classes, so they might be able to hold the generators, but you also have to think that the engines fold space to move, so lets! Your distorting space to move a station that is the largest thing mankind has ever made. That may be dangerous and distort the fabric of reality so greatly that it could cause serious reprocussions because you gotta fold space not only over distances, but also make them large enough for an entire station to get through it.

Of course this could all meaningless, I don't know. But if you want the reason they didn't put it in the game: Maybe they thought moving starbases would make trade less useful because instead of having to build chains of bases, you could just have a base move along right with the freighter and the same with fleets, industry, and influence. they might as well add in a new ship that provides the buffs but make it extremely expensive. Or maybe because they didn't feel like it. If you don't then make or ask someone to make a mod that makes an extra starbase modual that adds +idk movement. Hopefully this answers your question.

I'm not so sure about having the benefit apply to both friendlies and enemies. It might be realistic, but I'd avoid them like the plague. Why risk boosting the enemy's gear when you could just use the space and money to put another weapon on your own ship? It basically runs into the same problem that milbases run into in the endgame phase: boosting nearby ships by a few points isn't worth much when you have capital ships slugging it out with potentially hundreds of points of damage.

That said, your idea isn't a bad one by any means--you could make "carriers" that accompanied fleets of fighters and increased their speed, range, etc. It would help put fighters on even footing with the megaships you encounter lategame. And that's not even counting how useful they'd be early to midgame...

Could be interesting, but I think these would need to be high end improvements. Or at least that's the way I'm thinking. They could allow starbases late in the game to stay interesting, but not overwhelmingly powerfull.

For me the only reason to bother with mil starbases is if you're losing. That generealy happens in the mid game or late early game, which is when a starbase is most effective. After you beat your enemy back they're pretty worthless.

I personally love the idea of these starbases, I'd love it if the balance of the game made it so you NEEDED to build at least one to protect a key sector. Sadly, this currently isn't so...