And actually, I think that's the rational approach. Updating is a horrible experience. "Hey, guess what! You can't do anything while these 10 apps are updating. And guess what, the one you need is in the back of the queue. And a large game is in the front. You're not getting anything done for a while!"
Background auto-updating should be the default on all OSes.
If you tap an app icon while they are updating it will be given priority and moved in front of the queue.
And then the foreground app will have slower network speed and performance which given that a mobile device is a bad thing. If I need to quickly check mail I want that to be the only priority of the phone.
The current behaviour is just fine. Many poeple are just waiting until the device is plugged in at home/work before updating all apps.
This is not something users should have to think about, at all. "Update" shouldn't be in the user's vocabulary. Sure, some people are interested in that level of control, and for them there should be options to configure it.