To “put a bow around” the Seth Rollins finisher story, the change was made because Vince McMahon didn’t like the Curb Stomp. He started to voice his displeasure more and more over the last couple of months when Rollins was doing stuff with Brock Lesnar.
Vince hated the visual of Lesnar having to “lay there like an idiot” waiting each time Rollins had to give him the Curb Stomp. Vince put his foot down (pun not intended) after Wrestlemania 31 and gave the edict that Rollins needed a new finisher ASAP.
Once Vince makes his mind up about something, it's tough to talk him out of it. He does have a point though about the move requiring a guy to already have been knocked out by something else first and it really limiting the booking for some of his finishes, especially for a guy that Vince views as someone that should be stealing wins/winning out of nowhere.
It’s also true about wanting a move that was more versatile, concerns about concussions, concerns about the move being related to street violence, etc. but the main point was Vince didn’t like it and wanted a change.