Tumblr has an excellent marketing opportunity here. By reversing the update, they could be the one of the first major websites to acknowledge their user-base’s concerns and actually take action to correct it. This would earn Tumblr staff a lot of much needed goodwill. People would be so thankful, it would probably actually move their approval ratings higher than they were before this debacle. From a business standpoint Tumblr needs to realize the best move here.