I don't think that justifies the harm it does to regular people, but it is a lot less sinister than just CYA.
I actually blame tech media who capitalize on every "malware in the Play Store!!!" story a lot more, and the Apple apologists who use any news of malware on Android (even if it only applies to people downloading pirated apps and sideloading them with root) to trumpet how insecure Android is. Personally I think that bad press is the primary driver behind the modern policies.