Allow all games. Remove the prohibited games list.
The Twitch community is composed of people from around the world, coming from unique political backgrounds and cultures.
Prohibiting games enforces a specific view of the world to the Twitch community as to what is acceptable or not, censoring content with valuable gameplay and cultural content in the process.
As of this writing, the list of prohibited games are either due to violence, sex, or any game with the "Adults Only (AO)" ESRB rating. While this could be argued to be a good thing for kids, Twitch has already a "Mature Content" flag in its channel settings for this specific case.
Responsible adults however are not allowed to take the matter into their own hands and are forced to stream and listen to content that do not fully match their own values. This is in my opinion unacceptable since it hinders the creativity of the video game art form and its economics.
This is not just limited to the entertainment factor of violent and sexual content, but also derivative content that could not exist without those elements. For example, Manhunt 2 contains in my opinion a very strong anti-violence message in its endings depending on the player's actions throughout the game, but said message does not make much sense without the censored content. Similarly, HuniePop can in my opinion empower shy people to reach out for real life relationships through the tips given by the characters and by gamifying their fear, but would have a lot less impact to them without the naughty rewards.
Regardless of whether you agree with these opinions or not, the point is that even the most insipid-looking game can have a positive effect to various people, and blocking such games would prevent people from benefiting from them.
Please allow responsible adults on Twitch to enjoy the content that they want freely.