I've been really confused as to what all the hubub is about. I think I saw the sidebar for about 4 seconds on each of my installs before I hid it forever. I tried to reenable it to see what people were complaining about but couldn't find it within 10 seconds so gave up.

AFAIK, you can't enable them without resetting things in about:config. So it's a "big red button", and that's a good thing.

Keyword: currently

They said they'll create a Bigger Red Switch (TM), so this interim solution is better than nothing, and it's going to get better.

If they're breaking their usual silence to talk about it on Mastodon via an employee/developer, they should better keep their word, because they're on a razor's edge there, and they'll be cut pretty badly if they slip on this one.