Back in December, Peter Bright reviewed Windows 10:

App availability, more so than any functional limitation, has been the biggest sticking point for Windows Phone. Too many apps that too many people find too important to live without haven’t been available; even when they are available, many apps remain limited in functionality and maintenance when compared to their iOS and Android siblings.

UWAs are Microsoft’s best shot at turning this situation around by greatly expanding the audience for any app built for the UWP. Still, the company has a tremendous amount of work to do if it truly wants to fill the app gap, and it’s not immediately obvious that developers will help it do so.

First, app developers have to care about desktop users. Plenty of app-based services lack not only a desktop app but even a fully fledged website because the app developers simply don’t care. Consider Uber; although it has an online presence for various aspects of account management, the car booking capability is entirely app-based. Without an app, you simply can’t do it.

If you threatened to either take away someone’s phone or their desktop computer, most people would pick the desktop. 

Mobile devices are where the majority of our computing experiences happen and this is the very place Microsoft has yet to establish itself as a legitimate contender. 

As Bright points out, I’m just not convinced anyone—including businesses and developers—gives a shit about The universality of Windows Apps except Microsoft.