I think you have really nailed it. In the PC era, hardware became a commodity, but operating systems were not. Operating systems were closed and proprietary. Microsoft's closed OS dominated on commodity hardware.
But today operating systems are a dime a dozen like hardware. Fragmentation is not an obstacle as long as your platform connects to the network and just works without annoying problems. Portability is the important factor today. Your Internet device just has to work without a lot of hassles. I don't want to be a systems administrator. I just want the computer, phone, laptop, netbook, tablet to work and connect to a lot of other devices with ease of use.
All well and good when your network is the internet, and the only networked application you use is a web browser.
I can appreciate that you don't want to be a system administrator, but in the enterprise somebody has to be. Machines built by and for people who don't want to be system administators predictably don't have the administation capability built in and then they become a PITA for the people who are system administrators.
I've heard more than one person talk about how much they love the Mac they use at home, and how much they hate the PC they have to use at work. They blame Microsoft for having some kind of evil supernatural power to make their company use that OS instead of buying Macs. There are reasons why there's a PC on their desk at work, but they don't care or want to know what they are, they just complain that it's not how they want it to be.