There are certain musicians who make full use of extended range instruments and where it's completely incorporated into the music they produce, so a four string wouldn't work at all - Steve Lawson and Dylan Desmond of Bell Witch are two that jump to mind. Six and seven string bassists respectively, their music would be impossible on a four string.
Then there are guys like me, who're exclusively five string players, who's heroes are almost all four string players, but do so as a way to make "normal" bass playing easier.
The point is, I am a five string bassist, I play better on a five, am more inspired by a five and find it easier to transpose keys on a five - leading to more work. So from my purely subjective viewpoint, yes, extended range basses have lead to better music.