While we understand that there may be demand for an even larger variety of material parameters to be used with Enscape, there'll also always be restrictions due to Enscape being a real-time renderer. Still, as hardware gets better and better, you can always be assured that we'll definitely keep on improving and tweaking existing material output!
Furthermore, adding or supporting too many material parameters could quickly make Enscape too complex, which is why we generally strive to support the most used parameters.
Still if you have any specific inquiries/implementation wishes regarding this subject, you can also contact us via firstname.lastname@example.org! We're always happy to assist and receive feedback.