@FSWer it is easier to glide on an edge, because only one side of the blade is touching the ice. So there is less to slow you down. When you are on a flat you are on both edges, so you are going to go slower because of that. But if you can't balance on a flat it is hard to balance well on a edge.
Also, when skaters and coaches talk about being "on an edge", they don't just mean being on an edge when you start or finish a move. They mean being on the edge for the entire move - and they mean being on a clean edge, with no wobbles or scrapes. That is something that takes a lot of balance and control.
If you ever get the chance to look at the ice after really good ice dancers have performed, you will see that they are on one edge or the other for almost everything they do. They hardly skate on the flat of their blades at all. When you think about how fast ice dancers move, and how complicated their moves are, to be on a clean edge for all of that is really an accomplishment.[/QUO