I don't think so. What can Cotto do differently? Canelo still improving every fight. As long as he keeps that right glove between his chin and Cotto's fist during the early going when Cotto has max snap like he did tonight, theres no way Cotto will ever beat him. Cotto would be better served to go beat up Andrade or someone at 154 for a belt before riding off into the sunset. Canelo would be better served outbidding K2 to get the Lee/Saunders winner and getting a bit of top shelf full 160lb experience before making a GGG super unification.
Are you high? Cotto would get starched next time. He was feeling Canelo's punches pretty strongly from round 8 an on. Some think size had something to do with this but it had very little to do with it. Cotto simply had a hell of a time connecting. Canelo rolled or slipped 95 percent of the punches.
How about no, it doesn't warrant one? Canelo won clearly enough, and it wasn't so exciting that it calls for one either.
After GGG-Canelo, I think this fight was clear enough in that no rematch is needed, the aforementioned fight is more interesting to me at the moment. Not that I'd say any differently if the fight was REALLY close but still.