What seems to be missing isn't the CONTENT... Those are MIDI files, easily ported. Your basic problem with WS's is that they use an arpeggiator paradigm for playing things. Chords are not revoiced into instrument accurate voicings, lines are not played with voice leading, and patterns don't drop in on each other (like calling up a fill in the MIDDLE of a bar) and go to a particular destination (like a fill that changes to another variation, or an Intro that goes to the selected variation).

The mode of operation is far more computer-like, cuing up 'chunks' in advance, rather than the natural, musical flow of arranger operation.

Will it ever change? I have my doubts. Unfortunately, WS's are primarily sold to people who have NEVER played an arranger, and their needs, rather than ours, becomes a priority for the manufacturers.

But make no mistake... there is a TON of stuff that an arranger does that you never even think about (voice wrapping, complex chord generation, incorrect note correction etc..) that WS's have not even STARTED to address. I have my doubts they ever will...