This seems like a ridiculous point. Basically all software doesn't allow downgrades. Sure, if something happens during install, there's modern safeguards to prevent bricking your device, but upgrading software is usually a one-way street. It's why major companies have tiered rollouts of new features, beta programs, and developer previews.

To a corollary: Would you trust a software development team who doesn't trust their feature enhancements enough to where they provide an option to roll back the software? It would be like a clothing designer saying "Actually, buy last years runway, this year's might have some issues..."

As a user, I get 'undo' functionality because I'm playing in the sandbox. I trust that the sandbox is sound if I'm able to use it, and trust it will get ever-better as time goes on.