I love turnkey, and so do a lot of people. Who wants to fuss with installing new software, etc.? That's my perspective.
Closed-systems are much easier to make turnkey, but they aren't the only alternative.
Just because something is open, doesn't mean that it can't be simple. It CAN be tinkered with, but it doesn't have to be to make it work.
That response is shorter than I'd like, but I have to run unfortunately.