ARAM and Rotating Game modes

As a casual gamer I often want to have a quick, yet competitive game without worrying about farming and also being able to try new champs and builds. ARAM should be that mode, however you a) can't choose your champ and b) it can often be uncompetitive because one team's randomly assembled comp stomps the other (e.g. has tank, supp, cc/ poke while you have 4 melee). I think dominion/ ascension do the job perfectly, but we don't even get them anymore and I don't understand why. The argument of resources required to run them I think is just an excuse, since we used to get a different game mode every weekend. I think this game is a lot less fun for it. Who benefits from turning off rotating game modes? The SR fetish? :(