I don't understand this. Why use sex to sell something totally unrelated? What does gaming on Twitch have to do with any of this? Same with Youtube personalities who do this, like that girl who "taught people Japanese" while she gave strategic shots of her cleavage wearing cat ears. WTF? There's porn sites for that. Get that shit outta here. It's a thinly veiled attempt at getting more views in the most base and primal manner possible and shouldn't even be allowed.
Even some people that don't want to do it, and find the process to get ready to stream this way feel pressured to do it. In the last thread on this subject someone posted a video of a person that explained the process, and it seems like it sucks. Though I'm a guy that don't feel the need to wear make up, just throw on a shirt, and I'm ready to go anywhere. Oh that person talked about how uncomfortable those bras are, and some put them on very tight for more effect then stream for hours.
What can you do though, just stick up for yourself and don't follow the crowd. Be you, and if you are a twitch viewer, just don't click on them.
And yeah, if twitch is doing something fishy for more twitch.com hits, not cool.