Why would one support a united Ireland if they are not Catholic?

[useful idiot]

The idea seems pretty silly now. The UK and Ireland are both fairly well off liberal countries. Being in either is a good thing, so I don't understand the gripes of the nationalists or the unionists in this debate. I can understand why the Protestants had a seige mentality that caused them to do the things they did(although not really excusable), and I understand why the Catholics turned to violence as a means of fighting oppression(again, not particularly excusable). These questions should have been put to rest this past decade, but for some reason the electorate decided to jump to the two more extreme parties instead of the UUP and SDLP. Frankly I think it should just be that Ulster democratically decide which country they should be a part of, and that be that. Right now they would continue to be a part of the UK, possibly due to demographic changes they'll choose Ireland later.

The only real reason I can give for staying part of the UK is that Britain's economy is probably more structurally sound, and that transferring the entire government administration in NI would probably be a gigantic headache.