You also have to consider the precedent this sets. Now Riot can look at something unpopular about League, and just remove it. Rather than putting in the effort to save it, they can just do away with it. How long before Twisted Treeline gets the trigger pulled on it? Is ARAM popular enough to save it from being put down? Will season 7 be the time when all we have left to choose from is SR and custom games that take place on SR?
That's a horrifying thought, and yesterday I'd have called you crazy for suggesting it. Now, I'm having serious doubts. Players really do not like this "nobody plays it, time to get rid of it" philosophy. What if they decided to do that with champions? Galio would be the first to go. Urgot a close second.
Players aren't just angry at the removal of a game mode, they're mad at the idea behind it and what if could mean for the future.