Historically, demand dwindled and almost disappeared a few years after the PSS keyboards were launched, and from an economics point of view, the economies of scale meant that Yamaha and others could produce a full size version for the same price as the small key version. They could make still them, but choose not to, I guess.
There was some aversion from music teachers as well. There still is, I will not teach anyone (more than a few lessons) who has one. They have to have something with full sized keys.
The Reface series is aimed at an entirely different market sector - portable retro. In fact, they've probably created that market sector almost single handed!