Yes, I must hate choice and fun, apparently. I couldn't be that part of the fun of the game modes is that you don't have forever to play them, making you enjoy them while you can.
The fun of the game modes is how fun the game mode is, getting strung along for several months afterwards is what most normal people consider the "unfun" parts. It's more variety which keeps the game fun.
Since they are only around for a short time they don't have to routinely balance them. If they make a dedicated rotation then resources have to be pulled towards it because "These are the only 10 viable champions and I cant play anything else" shit storm of forum posts.
Look at Twisted Treeline, Dominion, and ARAM, they obviously give little to no fucks about balancing the "lesser" game modes. What's one more shrimp on the barbie? Hell, put a disclaimer saying "these modes aren't as balanced, just have fun and chill out" (not like it'll stop half of the mouthbreathers from having an aneurysm every single game, but what can you do? Why fuck up a good thing for the few bad apples?).
Have you seen how many URF threads popped up the passed few days? Both loving it and hating it, now imagine that for EVERY featured game in their rotation. FOREVER. You wouldn't be able to read the forums.
Oh no, whining threads, we sure don't have a bunch of those about the core game or anything. Might as well remove that then!
So in fact I really do like choice, like when I chose to call you a fuckin' idiot.
Good one, sure makes you look mature!
So yes, again, you do hate choice and fun, have you ever played Smite? You should look outside your bubble if not, they have a rotation just like suggested here, and oh my god they manage not to blow up the universe somehow! Hell, they give first win of the day bonuses for each of their several game modes, but that's a different story, I'm sure you'd vehemently oppose that as well.
The whole point is, it's a choice. How are you personally affected by the mode rotation? Oh no, the forums? You can choose not to read them! Not everybody treats this game like a 9-5 job and just play ranked every day, some people just want to play for fun, and a rotation is variety which keeps things fun. Monotony is not fun.