On one hand, I don’t particularly buy albums because of artwork. I can remember one or two times doing it with not-very-good results. More often I use album art as a way of quickly determining which albums don’t require a second look---for example, any album with people in generic r&b, country, etc., artwork usually gets glanced at at best.
On the other hand, I am a big fan of the way good albums use artwork to enhance and/or augment the themes of the music. I consider artwork an integral, though not necessarily essential, part of an album.
In other words, the good artwork always enhances a good album, but good artwork is not strictly indicative of a good album. And cliched artwork is almost always indicative of cliched album.