The attention span of guests. In the past, you could do a street show and have hundreds of people watch for 15 minutes or more. Now you cant get then to even come in close enough to commit. That's why the crew has to use mikes now. People today are too bombarded with media every day so when they come across an event like a street show or a musician or anything else not presented on stage with music, lighting, and costumes, ie "Spectacle", it fails to register as "worth my time." This may sound cynical, but honestly, that's the real reason there aren't more craft demos as well. You cant bring back the old SDC because the culture has changed. Jumanji cant stay a board game.