Teams in particular recent had a massive security breach where the client could be drive through exploited to own whole orgs and any org connected via guests, right?

I use teams. It works well. Mostly. I like it. Mostly.

Same here. I do understand disliking Teams if you have used the more clunky alternatives, Skype for business for example. Overall though, I find it more useful than before if only because the cultural change it’s leading in my company where more direct communication is now being encouraged instead of Japanese business emails with 10 extra lines of boilerplate and extreme business language tacked on.

Security products are sold for security rather than other useful stuff like messaging, so it's really useless if it's insecure.