He's doing it because Konoha put his brother through this shit. He thinks it's unfair, painful, and sees it as the only way to express his feelings. Madara himself didn't look too empathetic in that last shot. He just looked all too happy to gain another Akatsuki member.Originally Posted by Penner
I really can't say if Madara's telling the entire truth here or anything. For one, his current persona greatly contrasts with the one he displayed in front of Pain.