As a power user, and software creator, I absolutely hate this decision. Side loading and power features are a main reason I use android.

That being said, as a grandchild, I also completely understand where google is coming from. A surprisingly high percentage of users do need protecting from themselves. They are so technology illiterate that someone random tells them to install something, "it will say it's not safe, but it's actually okay, just click approve" and they will. This is why HSTS exists, to prevent uneducated users from getting pwned, by preventing them from disabling safeguards.

So, having some system of "no really, I am a power user" makes sense, even if I hate it.