That last sentence is everything about the indie music world that infuriates me sometimes.

Personally, for me, it just adds to an artist's whole package if they can write good songs as well.
Also, songwriting doesn't count as contributing a single word/line (Beyonce I'm looking at you)

I don't think its fair to excuse poor vocal technique though. I don't you need to have a five octave range, but I expect my singers to be pitch perfect, regardless of genre.
Especially when artists like Freddie Mercury proved that its possible to do all the things you mentioned and maintain perfect pitch.

Good list, but I'd add Etta James, Ella Fitzgerald, and Ottis Redding.

I agree. The best singers know how to use their voice to express the emotion of the song and bring the lyrics to life.

I think, as others have pointed out here, a good singer is an incredibly subjective concept that largely depends on the genre in which you sing. However, I do think that there are several hallmarks of a good singer: