Cheesing the AI can be fun, sometimes figuring out how to cheese it is a fun puzzle-- but only if it's for a one-off quests. If it's something you repeat endlessly, then yes it's awful.
So if there were ONE quest where you have to survive by continually circling behind a giant asteroid from an onslaught or something like that, it would be interesting.
That said, why can't their be nebula on the campaign map, and having combat in/near them means more nebula on the battlefield, as in the case of asteroid belts? The AI doesn't get TOO cheesed by nebula as it is, and campaign combat really needs some more variety and differentiation.
See I don't see this as cheese so much as strategy and tactics. Cheese is using an unintended mechanic to cheat the intended difficulty of the game. At best it forces a tedious play style to be effective and at worst it breaks the game.
Environmental battles won't have this effect if they are properly implemented at the campaign level. They dont have to be limited to a single instance but they should never be universally effectiv e either or tactics become cheese.
I'll use the nebulae example because it is the most commonly mentioned. My own use of this scenario would be something similar to the campaign mission the coral nebula. Carrier fleets with fast response units excel in nebulae while slow powerful ships are weakened. So if you are being chased by a fleet with that composition it would be a good idea to fly into a nebula.
If the campaign fleet ai always actually chased you into one it would be cheese. If the campaign ai broke off the chase once you entered because it becomes a bad fight for the ai then it is strategy.
However to keep things interesting there are times that the ai WILL pursue; such as overwhelming advantage in numbers or if the faction is desperate for some reason.
A really great use of this would have the ai adapt to your strategy. So if you are a pirate group darting in and out ofnebulae to avoid authorities they will catch on and send an overwhelming force to sweep the nebulae if they have the resources or even move operations away from large nubulae clusters.
This wouldn't be hard to do at the campaign level and would make tons of things possible as far as strategy/composition effecting the way the game is played