The Wavestation seems like it's just barely on the older side of a dividing line between digital synthesizers and romplers. Take a look at digital keyboards like the Yamaha DX7, Roland D-50, Casio CZ-101, Kawai K1m, or Ensoniq ESQ-1. They're all synthesizers, you use them to make sounds. You can use them as preset machines (and I'm sure most people did), but they have a ton of possibilities for sound design.
Then came the Korg M1, E-mu Proteus, Yamaha SY85, etc. These machines are more like "a bunch of sounds in a box"--you buy the box, you get access to all of the sounds recorded in ROM. You get a bunch of standard sounds like acoustic and electric pianos, bass guitars, strings, saxophone, etc. These keyboards have no realistic sounds and limited opportunities for sound design, but they are incredibly flexible from a musical perspective. If I show up to a jam session or an open mic with a keyboard, that keyboard had better have a good palette of acoustic & electric sounds.
The Wavestation is a fantastic instrument but what keyboardists wanted in 1990 was, you know, samples of all the acoustic and electric instruments on tap, but the Wavestation had no acoustic piano or drums. The Wavestation was not commercially successful, even though it's a fantastic piece of gear. The revised Wavestation EX got acoustic piano samples and drums but it still focused on synthesizer-like sounds. Ironically, the synthesizer-like sounds are what people like about the Wavestation these days.
https://www.soundonsound.com/techniques/korg-wavestation-tip...
I have a Wavestation SR at home, and it's really cool, but I can see why it wasn't as commercially successful as its competitors.
The Roland JD-800 (from 1991) basically has the same story--the JD-800 is a digital synth made in an era when people really wanted romplers.
Both the Wavestation and JD-800 got recent rereleases in cute, miniature formats as the Korg Wavestate and Roland JD-08.