Most likely this change in the TOS and policy was caused by the backlash twitch got from the public after the twitch employees/staff were caught receiving "bribes" from gambling streamers. That could've snowballed out of control for the company and it would've been a really nasty situation for them so they acted quickly and made the appropiate changes. Props to them for that
Interesting, I don't think I've ever heard of it (not that I've heard much of twitch in the first place tbf). It's also odd since, well, why were the streamers hit instead of the staff? That's kind of more of an internal issue after all imo.
The platform could add a warning message on gambling lives and channels without completely banning it. There is no reason to ban gambling content just because there are kids accessing the website, otherwise youtube and every social medias would have to remove this content as well. Moreover, to educate people regards the dangers of gambling you can't completely remove gambling content from the internet. They must understand gambling exists, it's part of daily life, many people around them can be gamblers and their only option is to deal with this situation in a way they don't prejudice themselves.
Honestly, one idea I've always had for people to know that it's a gambling stream (and be irritating as well) is just to put it in a big red banner in the front saying "GAMBLING STREAM, WARNING!" kind of like those kinds of obnoxious adds. Directly warns people and also irritates usual gamblers to the point of leaving. Damages the streamer yes, but I think that's the cost for streaming gambling in the first place.