To be honest, very little progress has been made in the last 20 years regarding virtual instruments underlying technologies. (I still maintain that my Korg Z1 was the most advanced synth I ever owned, and I currently own a Kronos ... ) Just because, say MODO drum and bass didn't exist 20 years ago doesn't mean that their underlying code didn't [in this actual example, it was very old code released to the public, by steinberg, that very few were making use of, that a company [IK] decided to finally make use of. That's how this typically works].
Companies decide to pay the programmers for the work to actually do something (turn into a product) with innovations that stopped short of having their papers published -- or they don't, and that's how you get thousands and thousands of different kontakt libraries instead of innovation.
I've read physical modeling papers going back to the 60's, they're literally written on typewriters, and I can guarantee you way more people were active in the field of trailblazing on that side of the 20th century. In my opinion you'd have an easier time writing about how much progress has stagnated since the late 90's on anything 'remotely' novel in the field of digital audio and audio DSP.
I seriously challenge anyone to show examples of any modern trailblazers today in terms of DSP and the innovation of processes which have already for years now been far out of the uncanny valley.
The cost of getting away from samples in terms of research and development is huge, and none of these audio companies really want to foot the bill for that level of R&D.