My motivational song.
3:10 is one of the most inspiring things I have ever seen.
The best feeling is …
Interesting question. I suppose it depends a lot on whether these undesirables bring with them a true social cost. We can behave however we want, but if our behaviour starts negatively affecting other people then we should expect repercussions, and that could include urban design! However, if it isn’t behaviour-related I don’t see how it can be justified. Designing-out teenagers is straight up discrimination, and designing-out homeless people is simply pushing a problem somewhere else. It’s short-termism.