Now you will be surprised how many of the big studios still uses old vrs of any application, weather its Maya , mental ray or whatever The entire pipe line was build on a specific Vr, upgrading sometimes can take years.
But at some point there needs to be a realistic cut-off for inclusion. This would enhance the product and the user's experience.
For an example one need only look as far as how successful Apple has been with moving their users along. This improves their experience without the hindrance of legacy after a reasonable amount of time. Maybe AD could collaborate with partners on what would be reasonable.
The inclusion and support of things like DGS, mib_illum, etc is really and truly old and confusing. As an educator I have a hard time getting students onto the most modern approach for rendering. This is also true of some studios I have been to (shocking, I know). It leads to poor performance and complaints from users and studios that would be happy if they understood the choice they are making is poor. Instead they blame the software.
Sometimes removing the choice is easier than education and after a momentary sting, they will have better results and render time. Then Autodesk can phase out support for legacy features while maintaining a contemporary product with the best approaches being more obvious. . .which would also stem support requests and complaints.
This seems reasonable but I understand the scary nature of dropping support for some things. But for now there is little to no balance at all. Everything is kept forever and the layering gets to be too much.
It's damaging to the perception of the product.
If only AD weren't a veritable monopoly it might feel more like taking the risk.