Well, Rito is projected to make $1.6 billion this year. That's $1600000000. Quite a bit of money off of skins, ward skins, and icons. Yeah you can buy champs with money, but that's not the primary way to do it. I mean high level players might buy rune pages, so you have that.
With this in mind, how do you get users to adopt the emote system? Most players aren't gonna spend the money they could on a sale priced skin just to get an emote. I for one do spend real money to buy skins on occasion, but a few dollars here and there for a nice skin is one thing. But spending $3 for an emote which can be muted is quite a bit of money. It would make sense if it was only 50 RP, but that's not what they had in mind. Ultimately, I think if you want people to adopt emotes you don't want to make them choose between a nice skin or a few emotes. As of Nov 7. emotes will cost as much as a legendary skin! That's way too much.
Anyway, although I like seeing the emotes, they really do seem like a free feature to me, as do many others here from what I gathered. Ultimately, I don't think I'll be seeing anyone using emotes all too often.
I'm hoping Rito makes them free in the near future, and judging by the fanbase's reaction, they might do so in an upcoming patch, hopefully.