Somewhat paradoxically, I consider immutable distros to be a net improvement for power users and a bigger hurdle for casual users.

Mostly that's because immutable moves the pain in the ass to the setup part of the application/OS life-cycle, while theoretically eliminating the kinds of issues that crop up months or years later when something stops working, or when a custom config used to get it working originally breaks something else as things relying on it mature over time.

On the other hand, mutable distros make setting up new software a breeze (in most cases, anyways) with far more under-the-hood tinkering available and have a significantly lower barrier to entry as a result, but become difficult to manage when the user no longer remembers all the customizations and dependencies they have introduced.

So really, there will still be pains in the ass either way. Just kind of a choice on which kind of issues the user would rather predominantly deal with.