I sometimes destructively wipe my machines and I enjoy knowing my email is separate and I don't have to faff with my tag database backup. That said, I do also use multiple workstations - which it is also useful for.
I'm not very much into Mu. I prefer Notmuch as I find the TUI more elegant and it's completely oriented towards tags and searches. Mu also supports folders, and that made it a bit more complicated to me.
However, I still find Mu and Notmuch TUIs quite different.