Windows got the market share precisely by doing the same..
I'm sure Ubuntu's developers or the people distributing this version for Dell probably are doing the same thing.
The only problem is, I would think Joe Sixpack would get mad having to put a password in every time he installs something.
Maybe I'm wrong; the average user may only care about email and surfing. But just to gain the full web experience you have to constantly install some control to make the fancy shmancy web site work. I assume most would use Firefox; would they be putting in a password at every turn?
Granted this pain would subside and slack off for a time as the user gained functionality.