Oh yes, I do that a lot. There are only few vendors where I know I can use shaders out of the box.

The idea with artistic images I like a lot, provided the artist agrees... a simple box next to content advisory and so on, "my work may be used by vendors as artistic reprensentation of their product" would do the trick. And it should be clearly stated what is a promo image by the vendor and what is a third party artistic render. In fact if I'm not sure wether to buy a product or not I also check the gallaries to see what others did with it and perhaps to see it in different light setups.

I also like the idea of standarts for promos... RDNA used to check the promos before releasing a product. Quite some times  I had to redo or alter mine, which was annoying, but in the end I think it helped me make better promos.