I guess you have to think along the lines of how many manufacturers are there out there, what markets are they aiming at and what does their user base most likely use as a DAW.
For example f I was making DJ related hardware I would look to integrating with the most likely software DJ's use.
Considering how often different or upgraded models come out it is hard to keep track of changes hence why the Mackie protocol had stood the test of time I guess and why DAW companies cannot guarantee to be compatible out of the box with every brand of controller.
I for example have a Novation Launchkey 61 sitting right in front of me and another couple of keyboard controllers. The launchkey ties in out of the box with my Ableton software but also works great with SONAR using AZ controller.
Having said that, do I actually use the controls on the launchkey which are available to me? Short answer is rarely.
I don't use the faders for mixing although I could, I don't use the rotaries for controlling parameters although I could. I actually do use the transport controls when recording or playing back what I just played and I have set up some pads to do perform tasks like undo record and start again. I do very rarely use the pads for finger drumming.
I must admit if I was playing and controlling live I could make more use of the parameter controls but there again would most likely have already pre mixed everything and tweaked some non active knobs to look like I was actually doing something rather than performing to a backing track