Agreed, app stores bring the rest of the world up to debian c.1998 (in terms of ease of installation), and it's a nice thing, don't get me wrong.
I tend to use the terms 'vendor lock-in' and 'walled garden' in connection with proprietary app stores, and then point out to people that "hey, yeah, there's an app for that... but VendorX won't let it be in their appstore". This gets them on the road to thinking about the things their phone _could_ do, but _isn't allowed to_ by their vendor.... and that way lies FOSS. :)