Arguably management tools for all those devices, but that is very rapidly changing. The real reason is that no body has done it and said "this is how you do it

Arguably management tools for all those devices, but that is very rapidly changing. The real reason is that no body has done it and said "this is how you do it" and not that many IT guys are in a position to decide to try it and take the risk. The only technical reason would be custom apps built for window or .net, otherwise all of the pieces are there to do it for most businesses.