Those are rather different situations. Mist is only Ike's sister, Sothe is Micaiah's protector, and he was also forced for the entire game until this point. I'm pretty sure his clinging to Micaiah is one of the reasons people hate him so much, so if it's that extreme it would make sense that he's forced to Endgame with her.
I've never understood why people hate him so much, character wise. He's one of the DB members that is actually bearable, since he's not all like "Genocide for my country? Okay, yeah, that sounds okay."