The Twitch chat is half the value of the stream-watching experience for me.
The "character" of the Twitch chat is valuable. The manically insane hivemind, with all the juvenilia and "shittiness" that is inherent to it, is a roiling primordial stew of genuinely worthwhile culture. It's the birthplace of memes in both the vulgar sense and the higher sense of that word, and, to me, feels like 4chan in its early days. The ecstatic chaos of the chat during an unmanageably large event is a unique and deeply valuable thing.
It was why Twitch Plays Pokemon was such a massive phenomenon. Channels which set their chats to subscriber-only mode are shooting themselves in the foot.
I've always desperately craved a comparable live mass chat experience for non-gaming-related events, eg during a football game, or a televised cultural event or major news story.
>Channels which set their chats to subscriber-only mode are shooting themselves in the foot.
I think both chat modes (sub and free for all) have their place and time. I enjoy chats that are put into sub-mode, just to read a sensible conversation and have the streamer answer interesting questions, that she otherwise wouldn't have picked up on. On the other hand, some stream chats live off of the chaos that is twitch chat.
Recently I noted an anecdotal improvement: more gamers seem to be saying that a winning player "shit on" another player instead of saying they "raped" them.
It can be, what people describe it as though is it is the digital equivalent to going to for example a football game. There is going to be a lot of toxic statements/ yelling made there as well but overall it adds to the hype of the event.
If you are watching a match with 100k people on Twitch of course there isn't going to be any valuable back and forward in chat but the chat stream as a whole adds to the experience.
I've seen this model successfully used on a variety of small and medium sized communities, Metafilter likely the largest example. While it doesn't seem to generate runaway fortunes, it allows online communities to survive the onslaught of spam and trolls.