>In our case only the rack space is rented - mostly for security and access control reasons. The hardware is under our control.

Yes, this is exactly the current infrastructure I have for Level Extreme. But, for another company, also as is the case for pretty much most of the companies now, they do not want to handle the purchasing, installation and maintenance of the networking infrastructure. We have evalutated this is too costly and we prefer to leave that to professionals who will include in their package, the ongoing hardware upgrade, licensing, etc.