It was bound to happen eventually. I personally don't think the die hard Twitch viewers will care much about an ad popping up here and there. We are so use to seeing ads with YouTube, Hulu, Netflix and so on. Its almost like a default these days. And hey on the back end of this Twitch streamers will make a little more $ for themselves.
Yeah I think it's kind of silly, I'm definitely not going to pay it, but I don't watch all that much Twitch anyway. I wonder if uBlock Origin or AdBlocker will disable the ads like they do on YouTube.
I think they removed, or are removing, the 1 *free* Twitch Subscription a month thing from Amazon Prime also, but not 100% sure about that.