It's not just about the quantity, but quality as well. Many of the major apps such as Uber, Lyft and Venmo are still missing, and the app store is still largely a joke with the hottest apps arriving significantly late - if ever.
As a Finn and a Nokia phone owner, I'd love the company to succeed. I'm just puzzled about the level of arrogance they still showcase, as if they know best what customers "should" want. For example, I visited Nokia offices past spring and a very senior level executive told to a group of developers and I how he doesn't understand why people even need apps like Instagram and "Chat Snap App" [sic] when the Nokia apps work just as fine or better.
While I don't care much about "app counts", the Windows Store is ... laughably bad. Common searches return tons of trademark violations, and obvious crap apps. Ugly junk.
The "number" was never a problem, and by optimizing for that metric, MS made their store into a gross place. A joke, as another comment puts it.
The number of app on Windows Phone is no longer a problem. There are more than 240,000 Windows Phone apps as we speak.