PDFs are a mess - and a liability.
Imagine trying to edit a document written in 10 different languages, using 5 different alphabets, full of typos and with no clear structure. That's basically what current PDF editors are dealing with.
It's not the file format that's broken, it's the way we've been using it. And when 90% of government forms, 95% of legal documents, and 80% of medical records are stored as PDFs, we can't just scrap it and start over.