Given the advent of android tablets and ipads, most colleges or schools also release for these and only these platforms. Along side banks and other corporate entities, when you look from that perspective there is unfortunately a gap. Which is a catch 22 situation, you can't have apps without market share and without apps there is no increase in market share, the universal apps will address this issue however it is going to be a slow road. The app store for android and ios didn't get to the levels where they are over night.
However from a consumer's point of view who just uses, facebook, twitter, youtube, some calendar, sms and phone calls there is not any app gap. But it is the lack of games which their friends are playing (i.e candy crush), which is conveniently bundly into the 'lack of apps' argument.
The crux of the issue is that you need to have a windows 8 machine, with slat enabled to even start developing WP 8.x apps. They should really have given developers tools to be able to develop WP8 apps on windows xp and windows 7 that would have helped a lot, since a tremendous amount of corporations, small to medium businesses and even government departments are still running xp.
For me personally, If I really wanted to play clash of clans I can install bluestacks on my laptop and play it. Windows phone suits my needs as I have all the apps that I need and use on a daily basis.