Sometimes I think it's because the DAW manufacturers don't really view the Step devices as flexible midi controllers that keyboardists would choose to use in a DAW. This is probably Arturia's fault for equipping the original KeyStep with nearly zero midi configurability beyond changing its midi channel. Most of its controls and buttons couldn't be mapped to anything, other than the start/stop/record buttons. So when the KS37 and KS Pro appeared, they all got tarred with the same brush (if you'll forgive the probably-UK-specific idiom).
I chose the original KeyStep to use in my almost-entirely-in-the-box studio because it was the only mini-sized midi controller in Arturia's whole lineup with aftertouch. Though it seemed very obvious from the start that the KeyStep was not really aimed at me. Bizarrely, Arturia's MiniLab controllers do not have aftertouch even though in every other way they more accurately fit my needs in terms of features and configurability, but for me aftertouch is absolutely vital.