Computer history is paved with faults that, in technical perspective, should have never happened.
NeXT was not ahead of it's times. It hasn't been technically surpassed by any other product in the "next" 10 years.
So NeXT is one. IMHO, Amiga 1200, Archimedes and Sinclair QL are other ones.
It seems a mix of mismanagement and marketing (which maybe is still mismanagement).
Sic transit gloria mundi.