Stump et Al. are seen by their hip-hop collaborators, I think, as living samples, picked out of the musical spectrum because their voices have some distinctive quality that the Roots or Kanye West or Dr. Dre want on their track. And, indeed, all three of those artists are known for eclectic record collections—the first person sampled on Kanye's last album is Elton John—and for perfectionism. Stefani has spoken about recording and rerecording her two lines on "Let Me Blow Your Mind" for hours before Dr. Dre was satisfied, which is illustrative. He was perfecting a Sassy Temptress effect, just as Kanye used Chris Martin to add a little Gripping Melancholy to his track about returning to his hometown of Chicago. Adam Levine has an indisputably fantastic voice for the wistful soul of "Heard 'Em Say." In fact, our civilization would be better off if he sang only hooks and covers, though his projects should still be subject to regulatory oversight.
The mental picture of the collaborator-selection process I've settled on has the added benefit of not involving any of my favorite bad-ass rappers and producers giggling with adolescent excitement over the prospect of working with a gelled-up Patrick Stump. Rather, I see them burning the midnight oil as everyone else on their cross-country charter flight slumbers away, obsessively searching iTunes until they find the exact ingredient their next hit is missing. (All the while, they sip a refreshingly crisp Coors Light; my mind's eye has gullibly internalized this Dre-featuring Coors ad.)
Of course, my mental Coors commercial would be more honest if it showed those guys doing a bit of Billboard-browsing as well. Big-time sales success is not an abhorrent sign of mediocrity for rappers, as it is to a lot of today's rockers; for many rappers, the signifiers of cool and the signifiers of mass success are interchangeable. So it's likely that even the most artistically exacting hip-hop producers weigh Maroon 5's uncoolness against their chart appeal a little differently than I would.
This is not to say that rappers have always gotten that balance right—there was a steep learning curve. While some of the examples previously cited were significant hits, the more distant history of the rap-rock crossover includes a lot of disasters. Most famous among these is probably the soundtrack to the movie Judgment Night, which featured matchups like Slayer/Ice-T and Pearl Jam/Cypress Hill. Q-Tip's 1999 song "End of Time," with nu-metal pioneers Korn, was in the same vein. Those bands are all more sonically distinctive and technically adroit than Maroon 5, but the results of the collaborations fail for an obvious reason: Rather than featuring one distinctive element of a band's sound in a backing beat, the entire group goes full blast while someone raps. It sounds like what happens when a band's MySpace page starts playing while you've already got iTunes open; it sounds, in other words, like the kind of cacophony that people like my parents think all rap consists of.
But while I'm happy that things have come around to the point at which rap-rock synergism is worth listening to, I still wonder whether I'll ever get the indie hero/hip-hop hero crossover that I crave. If any major hip-hop producers are reading this, get in touch; I have lots of great ideas! Songs like Jay-Z's "99 Problems," Dead Prez's "Hell Yeah," and countless Beastie Boys tracks demonstrate that distorted guitar riffs can make for a great hip-hop sound, provided they're kept sparse and inserted into a song with surgical precision—and, come on, Jonny Greenwood and Jack White can't even tune up without laying down the most killer sparse-surgical riff you've ever heard! On the vocal side, Wayne Coyne and Thom Yorke could contribute ethereally beautiful and ethereally nightmarish hooks, respectively. (The Roots actually do sample Radiohead on Game Theory's "Atonement," but it's not at the front of the mix.)
In these last days of the record business as we know it, established indie-rockers are as good a sales bet as anyone else. So why not get the best rap acts and the best indie acts in the studio together? It might produce some great songs, it could move a lot of units, and—I say this with significantly less condescension than I would have a few weeks ago—it might introduce some vapid middlebrow teeny-boppers to bands they'll like even more than Fall Out Boy.