[it's partially obnoxious bloody-mindedness, but mostly just the fact that Karkat has no idea what he'd have to do to get a new room sorted out, and he'd rather yell at someone than investigate it]

No, you know what I don't want? I don't want to be on this worthless planet full of backwards grubhumping mammals, but it doesn't look like I get a choice. Just like you don't get a choice about what I do with this room, which isn't yours. What the fuck is your problem?