This would avoid the confusion to some, of saying that the key/mode of A dorian has a key signature of G. I’m all for making things clearer for people learning music. If a piece is in D dorian, I always put “D dorian” above the key signature of C. This makes it clear what mode/key the piece is really in.
I’ve read your replies, thanks for the comments and answers. I realised I was being provocative in suggesting a name change to a term that is firmly entrenched in our culture, and also calling a mode a key . But I was hoping to find some way of creating a disconnect between “key Signature” and the tonal centre of a piece of music.
If the key signature is misleading, it helps if the tonal centre or mode is notated. Recently, I was given a simple 17th century Playford dance piece with a key signature of G. But the use of C#, and the chord structure, made it clear it was in the key of D major, as annotated by the person giving me the music. However, if I was creating a walking bass line around a diminished chord in jazz, it wouldn’t help annotating it as a super locrian mode. I just have to know that half-whole tone intervals are used.
The discussion Key signature for writing in modes other than major and minor confirms my belief that the key signature just tells us the notes being commonly used, and any mode/tonal centre should be annotated. And sometimes using the “wrong” key signature, with more accidentals, helps people understand where the tonal centre may lie. E.g, using the key signature of F for a piece in D dorian.
This extract from the discussion quoted just above, sums it up nicely for me: 'The term "key signature" used in English does not translate exactly the meaning of what it is. In all other languagues, the literal translation would be "clef armature". So a clef armature is not meant to represent a musical key, but to simplify the process of reading music.' Thanks Flávio.