People pick bare walls because they're imitating each other, and the bare-wall look is easy to recreate. For example, Hannah Hart can make videos like this https://www.youtube.com/watch?v=OzYk2iOZqss#t=242 but when she built a studio, it looked like this https://www.youtube.com/watch?v=gjK2xgolAws The first one is more engaging, but people have this idea of what a youtube video looks like, and they just keep doing that because it's what they're used to.