I've been in classes where they do some of those moves. I think the instructor lacked motivation and imagination - thus she needed to resort to those moves. There is no reason to do stupid stuff on a bike to break up boredom. Boring teachers have boring classes. OTOH, if a class is planned correctly, there are some songs where the instructor will coach lightly and let the students become absorbed in their own movements. It can be very meditative. I, for one, do NOT want somebody micromanaging my every move.