I agree to some extent. Songwriters accept that they will probably never have their name in lights, so it's not like they are unfairly being ignored.
However, I don't like it fans of certain artists think the artist wrote the song themselves, and give the artist undue credit. I think this mainly applies with pop artists, when the fans say "OMG I LOVE HER LYRICS".
Also, I feel it applies to rappers, who write the lyrics themselves, BUT, do NOT, compose the backing music - so when the fans say "all of his songs have a really good beat to them", they are assuming that the artist came up with it themselves. I know on the whole, the rapper will have solely composed the music, or co-produces it, but on the whole, NO.
I don't think it matters with acts like Girls Aloud, who make no lies about they wrote it or not - they are marketed as a manufactured pop artists, who xenomania write their songs for, which I have no problem with.
What really annoys me, is when artists actually do write their own songs, AND produce it, but still are seen as just singers. When people say, "Wow, I didn't know they wrote that song", I find it really annoying. The biggest example of this for me is Mariah Carey, who, on the whole, doesn't get the recognition she deserves for writing and producing all her songs (except the cover versions obviously). She actually writes the melody, lyrics and produces the track as well, and yet is just seen as a singer.