I agree with both of you. Our wrappers are currently very tightly glued to the rest of the product, and have a lot of hacks (hint: PDFJS documentation is not very rich, they have barely touched their documentation since they came out). So what we have is in no good state to release, unfortunately :( But if someone does initiate serious work, we will jump in with our contributions.

But to your points: because there is no good open source initiative that does what PDFJS Express does, commercial providers like PDFJS Express and PSPDFKit are able to build pricy SaaS offerings.