Jazz (and pop) composers and arrangers work explicitly with chords all the time. There is support for this in Dorico, but there is a vast frontier that could be added. And even if you don’t work in a genre where you regularly name chords/harmonies, some of this frontier could benefit you too.
I would break down the feature space this way:
Level 1: Ability to manually enter and print chord names.
Level 2: Playback of chords. This could range from crude block chords without inversions all the way through “auto-comping”.
Level 3: Snap notes to chords / scales. This can include the ability for notes to change automatically when chords are changed. This can also include automatic generation of arpeggios.
Level 4: Automatic detection of chords / harmony.
Level 5: Automatic harmonization based on melody and chords.
Dorico does level 1 brilliantly, and it does a decent job on level 2, other than having any comping modes. And chords entered into Dorico pass correctly through MusicXML. Other programs do levels 3-5 today one way or another. (With regard to level 5, Finale did this for several years with a Band-in-a-box plug-in. That was dropped when Finale went 64-bit and has not been replaced. It was a little buggy but actually quite a useful program, offering dozens of harmonization algorithms.)
Celemony has introduced Melodyne 5 this week and chord support has been a major focus of that release, with comprehensive support for Levels 3 and 4. See this video: https://www.youtube.com/watch?v=VBy_JuYTuGM
Likewise, Steinberg’s Cubase has had comprehensive support for level 3 and 4 for several years. See this video: https://www.youtube.com/watch?v=tCAzECMjQOg
Here’s what I would love to see in Dorico in order from basic to far-fetched:
a) Option to color-code notes based on how they fit in the current harmony. If no chords are entered, it would be based on the key signature. If chords are entered then they would take precedence over the key signature. A scheme such as Green = basic tones (root and 5th,) blue = guide tones (3rd and 7th,) amber = color tones (notes that are in the scale compatible with that chord, red = notes not on the scale (which might still be valid, but worth double-checking.)
b) Snap to chord, snap to scale. This would affect how alt+up and alt+down work. There is already a bit of logic that respects the key signature and tries to keep accidentals sticky, but I am suggesting the next level, which is to respect the current chord and the scales these chords imply. Basically, Alt+Up/Down would not go to a red note unless overridden.
c) Options for notes to move automatically to conform to a change in the chord name.
The above 3 items would appeal to people who use chord names already. But they could be helpful to others if we also had:
d) Automatic detection of chords. This is tricky business because sometimes it is ambiguous, and often there are multiple chord names that correspond to the same pattern of notes. Nonetheless, programs like Cubase, Melodyne, Band-in-a-box, Transcribe and others have seen fit to offer something here. A person writing hymns might not really care about the chord names. But if it were easy to detect the chord names, that would immediately highlight notes that didn’t fit and might be errors. I could see that being particularly useful in full-orchestra scores where it is very easy to overlook pitch errors.
e) Auto-harmonization – like the old BIAB feature.
f) Auto-comping, at least in some basic styles for piano, guitar, bass, drums.