But limiting spawn to just stations is even worse.
This is not true. EVE for example shows that meaningful respawns help the game, they do not hurt the game. Making it painful when you die is a GOOD thing, as evidenced recently by the return of WoW Classic where even a same-level mob is dangerous to you as a solo player, and dying might end up in a 5-10m run back to your corpse. This brings meaning and value to all your gameplay, because you know if you do die, it's a big risk. Likewise, it is not imbalanced that you can have healers resurrect you, since it is limited, takes time, and takes another person to do it, making you appreciate that other player more.
EVE shows station respawn is just fine for a game. It's the default option of any game. Die -> return to a starting position. Almost every FPS game uses this. It's ingrained into gaming actually. Pretty much all games have you returning to some initial state after a loss; it's one of the most fundamental aspects of gaming, where developers then try to find ways to affect that through gameplay - for example in Overwatch, Mercy can revive teammates mid-combat as an ultimate ability. Keep that in mind - reviving to the battlefield is an ultimate ability. It's not the default. It should not be common. If every player in Overwatch could just revive in-place a few meters from where they died, it would devalue the meaning in the gameplay. The whole point of killing an enemy in Overwatch is they have to return to their spawn point. With 'free' or cost-based respawns, your enemy would come at you in the same meaningless waves of bodies just like in Overwatch.
The most pure form of respawns would be station-only respawns. It would be a fine gameplay mechanic, but no one would be able to explore the universe. Likewise, a cost-based mechanic where you carry 1 or 2 respawns on your ship - what happens when you're 50 hours away from the nearest station and you run out of respawns? The next time you die, you're completely done, and you lose everything. So some compromise that allows respawns in-place needs to be in the game to facilitate the vast playable space of the game. Otherwise, like WoW Classic, you have to run back to your corpse - except it's a 50 hour run, not a 5-minute run.
This is why the revive mechanic works, but only because of the uniqueness of Starbase where we have YOLOL and we're robots and other factors which make it make sense. This way a solo ship in the middle of nowhere, the solo can revive as many times as he is prepared for using his ship or some revival drones he bought/built, and the same mechanic does not give a large group an exponential value in simply stockpiling respawns before any conflict (which, since station respawns will be resource-based as well I hope, they could stock station respawns, which is good, because that means the station is very valuable and worth attacking!).
Another method to limit respawn could be to perhaps have basically a "robot body building module" that you can put onto a ship, but it takes resources and several minutes to build a new robot body.
Like other ideas, this seems like a reasonable suggestion. After all, it still costs time after you die - this idea is simply making the 'respawn timer' more interactive and limited to one-module per person, but basically you're saying, for example, "Give players a 60 second respawn timer." It sounds reasonable, but provides all the same problems as other free or cost-based respawn mechanics in that you know you have, for example, 20 respawns on your ship, and can throw away any single life you have in scouting the enemy or pushing a position and any defender who kills you off, it didn't really matter. After all, your 20 respawns on your ship, are 200,000 respawns to a large organized group who have backup ships and backup modules ready to go if yours ever stops working. Your death did not matter to the defender, you just had to wait 60 seconds each death to get back into the action and throw another body at the enemy. It sounds reasonable but does not avoid this very common thing many games do and get wrong.
Again, looking at games that worked, WoW can be a 5-minute run back to your corpse or a 10-second spell cast from your friend who revives you, and EVE only has station-respawn available. One of my crew mentioned how in EVE, they would sometimes hold up an enemy ship for ransom, because if the enemy pod was killed off, it could often be most costly to lose the pod than to just pay the ransom. When people paid the ransom, they let the person go, because if they didn't let the person go, then their reputation would be tarnished and no one would trust them going forward. This was because death mattered in EVE, and because each life had value. If someone holds you up in Atlas for example, you don't care, you fight to the death because if you die you just respawn for free with nothing lost except a gear set. However, in Atlas, ship combat did have some pirating, because you could in fact hold up an enemy ship and pirate them - because the ship was one life and was not easy to remake - and this led to good gameplay when it came down to ship-to-ship pirating and so on. Ship combat had meaning in Atlas because ships were not free respawns. Yet players had free respawns, and that devalued gameplay is enough to sour the rest of the game.
Some games get it right, and many others get it so wrong. In Frozenbyte's new game Boreal Blade, when you die, you're out of the match (in most cases). You don't get a free respawn. Your life has meaning while you're facing off against your enemy. One of their game modes, you can respawn right away after a death, and combat in that mode feels much less satisfying and more 'spammy' than defeating the other team in other modes where there's tension in your actions and every move you make matters.
This seems like a very simple thing that gets ignored and isn't too big of a deal, but it does cascade meaning (or lack of meaning) throughout the entire game world. It's a very big deal which is why I'm posting so much about it. We have evidence from other games what works, and need something that adapts to Starbase's unique environment to make it work here, while still preserving the meaning behind the gameplay.