Jump Gates are super convenient, no argument there. What I hate is finding ancient ones in an otherwise empty system - if they cannot be destroyed, then what happened to all those Precursor jump gates, few of which can still be found? That's a minor detail that has irked me over the years. If a JG is more of a stabilized worm hole, and the Precursors created them, should't literally every jump point in the galaxy have one. If they can despawn/destabilize/get destroyed, then why can't I do it? Or Invaders?
If players can destroy/destabilize/despawn worm holes, what about the Invader inter-galactic one?
-Lore-
Oh that's easy enough. They DO destabilize... with a half-life of roughly 146,000 years. Of being unused, since mass passing through causes restabilization. So to answer your question, yes they do 'despawn' the same way the sun 'despawns' but you don't see any tech for accelerating the process.
If fact, if you really want to go that far, why do all jumpgates have to have an artificial origin? Couldn't some of them simply have natural origins? Like a jump point that via natural processes over its many many millenia of 'lifespan' has drifted randomly into a stable configuration and will in time drift out of it again. It would certainly explain some of the weird positionings of them (into dead end systems with no planets).
Invader wormholes are something different entirely, they are completely artificial and require active energy expenditure to keep open. Based on Jump Points, to be sure, but with the conditions for their formation artificially generated (via unknown means) and tweaked to make them strictly one way (like jump points that are closed on one side).
-/Lore-
From a gameplay perspective, destabilizing wormholes do make sense in my opinion. If every jumpgate is an irreversable change to the galaxy, consider the situation of 2 large empires fighting. One side gets a decisive advantage, breaking the outer defences of the other, reaching its jumpgate network. In order to take advantage of this, it has to extend its own network until it touches the other's. Now the two empires are eternally locked into a jumpdriveless struggle until one side is victorious and the other dead. Even if peace is made some years down the line, there will always exist this highway from one's space to the other, with no way to break it or impede it. No clear border between the empires will ever exist again.
Essentially, jumpgates ARE your projection of power. Connecting jumpgates to a system is a way of saying "this space is mine, I feel I can defend it from aggression". But there is no way to reverse that decision. Every war becomes all or nothing. You cant just capture territory, since you can't connect your own power projection to the system without opening your ENTIRE territory to massive counterinvasion. At the same time, the enemy cant allow you to keep his captured territory since it presents a foothold into the soft underbelly of his jumpbridge network.
For Aurora as it is right now, that is actually fine. The game takes the form of fighting numerous AI opponents sequentially, since no AI opponent can give a human a challenge in the long term. But what about human v human games? Or multi-faction starts?