Perhaps we'll see active knobs on a higher end arranger in the future, if the companies feel the demand is high enough, and they will still make their already good profit (the latter is more important to them, of course).

Yamaha has recently been putting "active" controller knobs on their lower end instruments (arrangers) like PSR-E433 that can be assigned to affect filter cutoff and/or resonance (plus several other parameters) which can be done live on either voices and styles or both. (See short demo below)

We have a Yamaha PSR-E423 in the studio for quick digital synth sounds that have analog control, and the instrument was very inexpensive considering what it does. Some of the sounds, especially when layered, are pretty huge and have lots of motion and character, and the filter can even be made to self-oscillate. Strings, brasses and pads are especially affected. The knob movements can be recorded in the instrument's rather limited sequencer.

Maybe they are testing the waters and might consider these types of controls on the higher end models?

Certainly, it would be a good thing, in my opinion.

Ian