Google has let the AOSP apps languish, and has used GApps as a bludgeon to keep control of the parts of Android they care about. Having phones running secure kernel versions obviously isn't a priority for Google, nor is consistent, functional E911 (look at the VoLTE shenanigans with Motorola and T-Mobile!).

What is a priority is building and extending the moat of GApps, locking services into relying on Maps APIs, push notifications, Play Games APIs, etc. Replacing these APIs is a huge task, and many apps will just outright crash if Google Maps isn't on your phone, let alone Google Play Services. The only reprieve is to use F-Droid, which is not the most consistently maintained app store.