I believe that the majority of non-musicians relate to vocals in music, above all other aspects. Plenty of drummers primarily listen to the drumming on records, and guitarists listen to the melodic instruments, etc., because that's how they are used to communicating in the musical forum. But if you never learned an instrument, and you know how to talk, it's the sound of the voice that's most intriguing--a typical communication, but important nonetheless.
That's why, if you make pop-rock music, I think that on occasion, it is okay for your background instruments to be completely straightforward and verging on boring, so long as you have a good singer. A band can a write a song consisting of two dreary chords repeated, but if their singer is quirky/tragic/heavenly/insane and relates a human experience well in the lyrics, the music can be propelled forever. Cat Power made a whole career out of this tactic. I hesitate to say The Smiths would have been nothing without Morrissey, but take away Johnny Marr, too, and you've got yourself some jingle-jangle bar rock.
This train of thought was sparked by a Brooklyn band called The National. I like them quite a lot. But before I explain why, let me just say that on the cover of their record, there is a photo of a guy in a swimming pool, and he looks exactly like Nicholas Cage in C.Hi.P.s sunglasses.
Instrumentally, The National employs a straightforward rock sound--simple guitars playing nothing complicated and nothing particularly innovative. There are songs with piano and lap steel, and sometimes the guitars go off on solos that are reminiscent of roots rock, but get a little un-directionally wanky for my tastes. (For the record, I do enjoy guitar wankery very much, but only if it is composed, à la early Yes.) The National's songs are in four-four time, and sometimes they have a country edge. For the most part (except for the two songs that remind me of Sarah Records and Kitchens of Distinction), it is the kind of music that you can hear in a bar at any given time anywhere in America. Big fucking whoop, right?
BUT they have one of those singers. Their singer, whose name is Matt Berninger, adds a lot of depth. Indeed, he makes the band. His voice is low and manly, so much that it swaggers; he doesn't even really emphasize his consonants very much. Because of this, I have created a whole persona about Matt Berninger in my mind. I think he is the guy in the band who gets sort of drunk before every show, and he's never sloppy, but it makes him sort of sassy and depressed. Perhaps he is drinking to mask his depression. After all, he sings the line, "I have nobody left to forget/ I guess that's what assholes get." Matt Berninger is awesome.