I agree that it shouldn't really impact other streamers all that much. Other streamers might feel that they have to work harder for a donation, but its usually a different demographic that watches each. Streaming is a performance after all so if cleavage is what people are willing to donate for, then I say let them.
I do however think that Twitch should stick to its roots of being a streaming service for gaming, but its just good business to allow them to do all their streaming on their platform instead of having to switch to another for non gaming related streams. As long as a majority of content is gaming, it should be fine overall.
If people hate "booby streamers" so much they should just not watch them, simple as that.
I agree, the demographic watching booby streamers usually is very different than the ones watching 50 year old overweight men play retro games. Both offer a service, albeit very different ones. If booby streamers make you upset dont watch them.