Of course…if NeoHaskell is going to be an alternative language. But not if NeoHaskell is intended to be the “next Haskell” (version, standard, et al ) - as you so memorably noted:
These are things wherein you can’t simply “fix [fundamental choices] via imports” because they cannot be remedied by addition […]
…and when someone probably smarter than all of us combined (yes, that includes me!) discovers at least one useful denotational denotative semantics for mutation, I confidently predict mutation will be added to some Haskell implementation within three months, be it GHC or another new implementation.
Until then:
If @Liamzy’s comment is any measure…the most desired one would be the ability to change a binding’s value “when it’s convenient” i.e. ready access to mutation, without having to use ST, IO, STM, various combinations thereof, etc.
Eventually, most who persist will make the transition to programming free of mutation, but that doesn’t make it any less tempting: “if only I could change just that particular binding right here…”