-- The whole party including the protagonist is pre-made, to the point where every character looks unique and requires their own gear. But then again this is also true for modern BioWare games, are they JRPGs too?
I think that Bioware formula (at least companion npcs part) was heavily infuenced by JRPGS. [also, jade empire]
It's kind of similar to to the way multiple protagonists are portrayed in kids movies, disney and the rest - a band of misfits, each with different background, colorful personality, visually different from each other, everything a little over the top.
I don't think that euro/us crpgs used that aesthetic or this type of characters too often, before late 90s, in story-based games.
Jrpgs kinda paved the way for this stuff, and i think that Torment was one of the first "casualties". Obviously it was executed well enough, and was fitting the setting of Sigil, so no complaints (you even have rare, "non-likable" npcs like Ignus or Vhailor).
[In this line of thought, PST added to the decline. Devs that followed, mindlessly drew from the same pile of ideas, wanting to add some character flavor (or drama) to their characters, but often failed miserably - like bioware.]
Having played PST in my teens, i've always seen it as a spiritual jrpg sibling, not that far from Septerra Core or FFVII - which i played around that time too. Urban adventure? check! Wacky characters? check!
Story oriented? sure! Kinda half linear, half non-linear? yeah!
tldr. i don't know how to make a single point from all that, sorry