I think its the same with many styles of music. One generation create's the style and by definition that is middle of the road - they slowly become more experienced in what they are listening to and also become bored with too much of a good thing and therefore go one way (minimal) or the other (hard) and for a while the middle ground isn't catered for. That is until the people involved can get a new generation interested and they will start out from the middle of the road just like we all did and head out to one of the exptremes if they stay interested long enough. Its a well travelled path.

I'll confess to starting out with Hard House (which I still enjoy occasionally) and that was the same. Loved bounce at one point but can't bare it now but I listened to filth, funky, hard trance and all the other genre's along the way before finally settling on liking the funkier, middle of the road sound.