I'm actually pro-app store as long as it's helping apps to be malware-free. But I'm 100% against shutting out side-loading. Side-loading was never common let alone a common vector for malware, at least not that I've ever heard. But what it is, apparently (or we would not see these Google shenanigans), is a long-term threat to Google's own app store.
Some idiot executive decided this.