Dancing is a fine thing of course but because sessions tunes were originaly tunes for dancing, it does not mean that it should be limited to this. It has indeed already turned into something different. Just try dancing to your average session reel. Playing for dancing can become a little tedious too.

Possibly because they have moved on from being just music to dance to, is why fast 'Irish' sessions are more popular than 'English' or 'French' (danceless) sessions?

Old time sessions still seem to combine the dancing and the music pretty well however.