Here's some truth for you:
they never were popular.
They have always been niche, aside from a few key franchises - mostly under the Square umbrella. Final Fantasy, Kingdom Hearts, Poke'mon are big exceptions to the rule. For a jrpg, selling 200k is often considered a success. 1 million? Do you realize how rare it is for a jrpg, of any era, to have sold that much? Even in the psx era only games with the Squaresoft logo pulled that much weight.
The idea that jrpgs were EVER popular in the west is one giant, adorable myth.