Congrats on your KSP.
I've never seen an official explanation, but my best logical guess is that the KSP is primarily a sequencer, and all it's knobs are used for that purpose.
Some knobs can be changed/switched to an alternate midi #cc function, but then you will temporarily lose their intended purpose.
In other words, units like the Keylab range have lots of unused knobs and buttons that need to be mapped.... so their are preset mapping for those.