Most devices propose this feature because it is extremely convenient, like for your phone, consoles, etc. Maybe this could be limited to core updates only to limit the blast radius?
I have multiple HA instances and I forget sometimes to connect to all of them to check and apply updates manually. I would be extremely happy if that could be done for me 
The main reason this doesn’t exist is to protect your installation from Breaking Charges. They want users to check the blog post to see what is included in the update and see how those changes could impact the stability of your Home Assistant instance.
Yes I’m aware of that, and it’s a reasonable approach. However, HA has grown and stabilised tremendously in the past 2 years. I hardly remember having an issue after a core update, if ever.
I think the product is mature enough now to have that option. Although I would make this optional with a various other settings like: