Donnie,
I agree about the workability of MDF and even Corian (which I hate the smell of when cutting). One thing that sits on my mind is how nasty MDF is to router bits and the like. They certainly aren't cheap, and I do my best to select a 'good' speed for them to run as well as the right cutting speed. Having said that, I usually am working with some sort of cover of solid wood over the MDF cabinet just to make things heavier, heh heh. i even reverse cut with the router when I am near a corner for the reason that you mentioned about wood, especially plywood! Nothing like that little piece that you can't replace just zinging across the shop.
Now if I were a rich man, some kind of perfect material would be used regardless of price, but for now, it's almost always the usual.