Luke,
Will you be posting your emails here? Your one from the other day is very true for me. I am seemingly always writing for a specific audience.
I write etudes for particular instruments at particular levels. I write easily sung music for congregations and small choirs, in most cases setting a lyricist friend’s text. I write solos for beginning and intermediate bassoon and recorder players. I arrange pieces for woodwind quintet or double reed ensemble. Yeah, maybe kinda niche, but it also sets out parameters for me, points me in a direction, and limits my options. It helps getting started into focus and provides some sort of initial step. Then I can go from there.
Rare is the time I write music for myself. Closest I come are the piano parts to wind solos, when I’m not limited technically.
So yes, I do think having a target audience is beneficial. For me, that audience is most often participating in the music making rather than being a consumer of the music. I don’t know it that makes a difference, I want the music to be both fun to perform and technically accessible for the performers as well as enjoyable for the listeners.