I think Microsoft are partially to blame for the existence of these app stores. By ignoring package management they created an environment where software was hard to manage and frustrating to install for users.

I don't think I've ever met anyone over the age of 40, from a non-technical background, that has ever checked for service updates to a piece of non-Microsoft software, downloaded it, and then installed it. To this day most people don't bother beyond Windows Updates (and only install those because Windows screams at them about it).

I've met plenty of Windows 8 users who haven't noticed 8.1 is out.