I'm not sure how much stock people put into music reviews. Since Napster I would imagine the significance of music criticism has drastically decreased. There's just so much music and so much niche appreciation for any publication or person to have final say on the matter. The Grammys are bullshit, radioplay is bullshit, and historically valid publications like Rolling Stone are obsolete. The widespread availability and affordability of music makes the role of the critic less important. What I sense is happening is that the role once prescribed to the critic, of valuing and recommending music, is being passed on to the mass of listeners. As in, websites like Pandora and Last.fm which aggregate user data to point you as the individual to music you will more likely enjoy. Listeners today find music by the very particular blogs which best match their taste. I know for me, I don't care what any website says about a track, if I like it I like it, regardless of someone else's tastes. By all means, say a track sucks, it doesn't effect me as the listener, but it is also not very productive.
The role of the critic should then shift to one of wider cultural analysis. Music should be analyzed for its wider social effect. A song that sucks can still be worthy of analysis and interpretation. For instance, I think any of the recent Disney Pop sensations are worthy of cultural analysis even though I would never normally subject myself to those songs.