I could be misinformed about this, but my understanding is that it's because PDFs are considered software which is not only not covered by Asmodee's/FFG's license, but specifically covered under some other license. So in other words it's not just a matter of renegotiating the one deal between Disney and Asmodee, but also renegotiating the deal between Disney and whatever third party holds that right. And given that RPG PDFs would bring in a pittance compared to the size of the deals themselves, no-one can be hedgehogged to do that.Not the Star Wars ones. That's contractual, unfortunately. Tho' FFG did get permission to release PDF's of the additional specialties, but none of the rest of the sourcebooks. And those had to be bought direct from FFG, so I'm hardly surprised they're not on DTRPG. And even then, when I asked about it during playtesting of Stay On Target, apparently even the splats weren't allowed to carry a code for the specializations extract PDFs. Disney at their full greed mode.
It does make me wonder how they can do apps for Imperial Assault and such, but perhaps that falls under some other exception clause.