The problem with live guitar loops was always, yes, they'd sound great on simple maj, min and 7ths or sometimes dim, but what do you get if you ask for a sus4, or an aug, or an add9, or an 11th, 13th etc.?
Sometimes you'd get an additional note from a poorly matched sampled guitar so now you have a 7 string guitar, most of the time a wholesale substitution of a MIDI guitar chord was used, leading to a very noticeable change in timbre...
Guitar modes are getting better all the time. Guitar samples are getting better all the time. We are getting to the point where guitar modes on computer acoustics and electrics can barely be distinguished from a loop. But every chord, every extension, every open chord, every fret position are modeled.
THAT'S what we need in arrangers, not pre-canned audio loops with a minimalistic choice of chords and voicings....
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An arranger is just a tool. What matters is what you build with it..!