Stower,
I asked you whether you played melody on the bass strings with your thumb[or if you like, other fingers]or on the top strings.,just interested in your style.
Another question do you accompany songs or play tunes or both.
the English Song Tradition, [imo]is suited to both styles it really depends on the melody of the song.
Carthy had no problem playing Lord Franklin or Scarborough Fair in standard tuning.
Dave Burland has now gone back to playing quite a few songs in drop d or standard as well as DADGAD.
Carter picking IS MELODY BASED with chord strums in between.
its quite possible to play melody in open tuning,and play dyads[which occasionally become chords by adding a dissonace to the modal dyad ] this is done as you know by leaving the third note out,and it sounds very well for the English tradition[but its still a chord a modal dyad with an added dissonance].
I disagree with you about not adding extra dissonant notes to modal chords/dyads,now and again they can be appropriate,and can sound very good.
HOWEVER some songs do benefit from a clear definition of whether they are major or minor [ examples are Spotted Cow and Leaving of liverpool and Banks of the Lee]