Yeah, you know what's kind of sad? How many people say "It's kind of sad" and then watch and pay them money, anyway. That's why it happens in the first place: because it gets people's attention and money. If someone said, "Hey you, would you like to stream and play video games? yeah? Great! We'll pay you this much. We'll pay you 5x that amount if you wear a tight T-shirt". Wouldn't YOU do that?
Of course you would! Do you know why I think you would? Because you have a job. You have a job where you carry a badge, or wear a uniform, where you have fixed hours that you go out of your way to meet. You make all kinds of sacrifices, be it your dignity, your time, your love life. Do you think these girls enjoy showing their bodies off on camera? Not generally, they do it because they want to get paid, just like you, just like anyone. They're hustling, and this is what works. We all do it. We wear the McDonalds cap to sell burgers to hobos, single men, teenagers and young families; we go out and sell office supplies despite getting doors shut in our face by disgusted office managers; we work in construction and destroy our bodies over a lifetime or less just to pay the bills. We all hustle. We all make sacrifices. Just because you're uncomfortable with the choices they're making doesn't mean yours are any better.
TL;DR: Don't hate the player; hate the game.