The effort put in. Dragon flying requires constant attention and inputs, which is why it’s so much faster than static flight. Static flight requires no effort.
I’m 100% behind the concept of every mount should be able to do both if it is capable of flight. And we should have the option. And Blizzard should put the effort into making all mounts capable of flight capable of performing both.
I am in no way supportive of static flight at dragon riding speed though. Point and auto running at that speed makes no sense to me.