Well, personally I prefer feature-rich software. Moving Keppi to the direction of a music player isn't a problem. (However, I don't tend to implement player features unless someone requests them.)
Generally I prefer rich software too but I also enjoy simple stuff ("one thing well"-style, for example Textify
Will adding support for more formats be meaningful to you? Do you use lossless audio formats?
I think that some control (play/pause/stop) plus drag&drop will add a bit of flexibility and handiness.
I like the name of the program- keppi
sounds cool. By the way I know a single word in Finnish- kotka
(because of the city
). Curiously kotka
in my language and because I love cats I was rapturous when I first heard about this city and that was why I checked the meaning.