Is it really necessary to "see"?

I don't think it is necessary. When I'm hear an album I want just hear it. Don't care about the visual part.

No its not really necessary to see the visual art when I'm listening to music, but it always feels good to see that the album is perfectly archived, and the album art is shown when it is playing. I personally add album art to the missing songs in my music library cos OS X has the habit of showing the the album art as a thumbnail of the icon of the song.
Although it might not be necessary to see the album art when the song is playing, but it sure is good to have the album archived.

as long as the album art is correct when I add the album to my media player, I don't care about the visuals of the album. If I enjoy the songs and can listen to them over and over again with out being bored then I think the band has done their job.

I am fond of collecting music and album during my time. I want to hear them as well as see the album itself or the artist. for me this my total experience of reminiscing.