For one, without Google Play Services you have no Play Store. Unless you're going to prevent users from installing apps entirely, there isn't really another safe way to obtain apps. Additionally Verify Apps, SafetyNet, Safe Browsing, etc. are all part of Google Play Services. You _really_ want Verify Apps.
F-Droid and Racoon are ways to obtain apps. MicroG is an alternative to Google Play Services. How do these solve the other issues the commenter mentioned? Does MicroG include "Verify Apps, SafetyNet, Safe Browsing, etc."?
I understand Verified Boot, but how would removing Google Play Services damage security? It would seem to reduce the attack surface.