Based on your reaction I’d guess you probably weren’t the primary target of their rebrand messaging (covered in my second point). That’s totally fine and I am sure they know they will lose existing customers and future prospects. But the risk has a potential payoff of becoming distinct from other services while developing stronger relationships with customers that fit the new messaging.

As for the point of branding, I couldn’t explain it any better than one of the masters, Michael Beirut! https://glg.it/videos/michael-bierut-ptagram-brand-design-creating-logos/