If I'd never used a laptop before I'd probably do the exact same thing as the kids!
Keyboard and mouse don't give you any more autonomy over the application developers state machine.
I'm not sure I understand the claim of "being in control". The UX is different, sure, often. But that's not "control" over the design of the application.
On a touchscreen, I can tap. That's it. Select? Tap. Move? Tap. Highlight? Tap. The only one that makes sense is draging for moving, but even that's a pain in the butt because it often misinterprets the tap+hold duration that's necessary before it works. When I'm editing text (navigating, cut-n-paste, etc.), it gets what I want wrong more often than it gets it right, I mean like 80/20.
With the phone, they had a green field to design an entirely new UX for touch interfaces, so there's no legacy to blame.
Some people don't intuitively use trackpads so they'll use a mouse and if they discover touchscreens that becomes a feature that needs to come with any laptop after that.
It's pretty eye opening really. If it weren't for seeing someone close to me do it, I'd be in the same camp, wondering who in their right mind would use their laptop like that.