I feel one of the issues going for a form of elimination victory or just trying to halt the enemy expanding, especially on bigger galaxy games, is that you're forced to take over their system right afterwards and it takes a while to get rid of it.

Privateering in the latest DLC offered something great, which is you turn them into hunting grounds similar to Vodyani, where turn by turn, it destroys buildings and pop. This is something I think should be available to all factions when you conquer a system, where you can choose to either take it or turn it into a "hunting ground". The problem with privateering is that if a faction is allied with the pirates, this strategy doesn't work at all. Furthermore it opens up for others you're not at war with to attack your fleet and it makes you unable to utilize your fleet heroes.

By giving it to factions by default it would offer more variety when it comes to warfare, when those who wanna play tall can go to war without worrying about grabbing systems they don't want. It'd also add some strategy where if you don't want a system, you give the enemy or someone else a greater chance of grabbing it with it not completely destroyed, as the greater the system was, the longer it'll take for it to be destroyed.