Seriously though, is there another format that:
1. Can be easily and freely shared by email / cloud drive, including assets, images and fonts.
2. Supports form filling and saving the form data in the file directly (as opposed to sending it somewhere over HTTP). Basically the electronic equivalent of a paper form that can be filled, send by email and stay filled.
3. Supports (cryptographic) signatures that are again part of the document, and can easily and securely be verified by end users. This is a very important use case in the EU, where electronic signatures are based on cryptography, not "I pinky swear I'm John Smith" DocuSign.
4. Has perfect print fidelity.
We keep complaining about PDF (and rightly so), but there's truly no other format to replace it. The W3c / Whatwg / whatever could probably come up with one based on web technologies, but they haven't yet.
There's Epub which solves a very narrow use case of PDF (electronic book distribution where perfect control over presentation is not required), but nothing that solves the "business" use cases.
Adding JS to PDF seriously undermines these benefits. If Turing-complete logic can draw arbitrary images on the document, you can no longer have any print fidelity at all, and what you signed cryptographically may have said things you didn't know it said. It may start interfering with #1 if email systems start blocking "malicious" PDF features, too. Only benefit #2 survives.
I have no idea what the folks at Adobe were thinking when they decided to add this feature that could eventually eliminate most of the benefits of their product.
None of this is to say that the Doom implementation is anything less than a very cool hack.
probably the same thing that netscape did when adding javascript to the web. "now we can add some basic client-side validation to these forms". PDFs can be used as form templates, so having some basic validation is reasonable.