Did you read my post? Sure, Apple "App Store" revenue is greater than "Google Play". But I was referring to services (which are in no way linked to the client application on iOS/Android).
Services are absolutely linked to their client applications. Just yesterday you were arguing that cross-platform support was one of Spotify's greatest strengths as a service, now you are arguing that client applications are irrelevant as far as services are concerned. It can't be both.
I understand that it's advantageous to the user to be able to access services on a greater number of platforms, but there is not a lot to suggest that this is a major selling point for Spotify or other services.
Also, I didn't mean to imply that Android is the "most important platform" for Spotify.
You didn't imply it, those were your exact words. It doesn't get much more explicit than that.
Apple's new streaming service would almost certainly support Windows, as it's highly unlikely that it would be unbundled from iTunes, which has been supported on Windows for over a decade.
As you said, can I have some figures to back this up?
Did you not read the link I posted specifically addressing this very point? The split is 52% mobile clients(including tablets, split 42%/10%), 45% desktop clients and 3% web clients(which I think can pretty safely be assumed to be desktop users, as well).
That's obviously a pretty even split, but when you look at market share of each platform(~90% Windows, 9% OS X, 1% "other" on desktop, ~%80% Android, 15% iOS, 5% "other"), the math indicates that Windows(roughly 90% of that 48%) comes out on top, although admittedly it's a pretty close race with Android).
This doesn't account for regional differences in marketshare, which tend to vary heavily. Spotify hasn't released any numbers regarding usage by country that I can find, but Android's marketshare tends to be lower in more developed countries(substantially so in English-speaking countries), so Windows may have an even greater lead than global figures would suggest.