It's kind of a dead market.

There are a few who are passionate about control surfaces, I was one.
I went as far as to make a control surface dll for Cakewalk that permitted chaining up to 5 bcr2000s in a 32 channel mixer with 4 page assignable vertical encoders per track, usable and sends, comp,eq.

When I had to quick mix for clients I used 4 bcf2000 Control surfaces and still have them in front of me even after closing up shop. but find myself just using a mouse.

I am of the mind the control surfaces are largely met with meh outside of profession situations where you must mix fast.
That limits the market.