Why? CM is legally prohibited from bundling Play Store, Google apps like Mail, Youtube, Maps, Currents, Now etc. etc.
In fact, Google sent them a C&D for doing so.
http://phandroid.com/2009/09/25/cyanogen-gets-cd-from-google...
If users cannot obtain them from (sometimes shady) filesharing sites, how many using CM currently would have installed it?
I replied that CM's popularity is a direct result of people committing copyright infringement by providing and downloading non-open source Google apps. Won't cutting that off reduce the popularity of CM?
AOSP is open. Android? Probably not so much, since it includes the Play Store and Google Apps in common usage of the term. Don't you see the technical distinction between Android and AOSP?
The only way I can run a "modern" version of Android on my Viewsonic Gtablet is by using CM, and I don't care that I don't have access to google play on it. The Amazon marketplace is free to download and install and the apps work great.