[mcny]

The way they've done this basically has users begging for it though because the alternative would likely be excessive battery usage for some things and no updates for others. I'm on lineage but most people aren't fortunate enough to have nexus devices or don't know/care enough to run anything other than what comes with their device. I think moving everything possible to play services is helpful for them.

[larma]

If it was about the features, they could (and should) have released these bits as part of AOSP, as free software.

Not doing so reveals there actual reason: control. Forcing every manufacturer to ship Play Services and thus being able to force various things on their devices is a major financial benefit. It also ensured that Amazon or Nokia were unable to set up a commercially viable Android Fork without Google.