I agree with you in principle bbblue: better to make the KPA play nice with readily available, standard MIDI controllers then release yet another proprietary controller... but that's just in principle. In execution a generic MIDI solution never seems to work out quite as well. For one thing, these other 7697 footcontrollers you mention - I can only count 10 or so, and half of them have been discontinued. Of these, each has its quirks: this one requires AC power, that one will only send PC messages, this one over here is so massive it's changing tidal patterns and so on.
Moreover a straight MIDI pedal won't be able to do cool stuff like display current patch names, tuner output, or current effect on/off states; not unless KPA were to really step up with sophisticated and largely proprietary MIDI output conventions, which I can just about guarantee won't happen.
And you can't assume that "all this Midi stuff is allready available in the KPA"; there are actually a lot of crucial parameters without corresponding MIDI CC/PRN messages at the moment.
I'm running a homegrown MIDI pedal for the KPA right now (and I've already thrown too much money at it and met with too many comprimises.) When the Kemper controller comes out, if I can afford it, I'm likely to buy one - because it's almost certainly going to work better. (I'll very likely use it as a master to change settings on other MIDI devices, however.)