If you were to ask me five years ago what my view on pop music was, I'd probably tell you it was god awful crap. That said, my musical taste has evolved over time, and I've come to accept a lot of pop artists (this may be in part due to Katy Perry being hot).
So here I am listening to music in 2010, at the peak of auto-tuning and processing the hell out of anything you can MIDIfy or record with an audio jack. Auto tuning is what double tracking was forty years ago, and I like it. I liked it twelve years ago when Cher did it with Believe, and I loved it two years ago on Kanye West's 808s and Heartbreak. And I like whatever the hell is being done with Justin Bieber's yet-to-ball(s)drop vocals.
Baby is one of those few pop songs that have a vintage pop sound while still sounding relevant in its own time. Granted he says the title word way too many times, but hey, chances are you LOVE The Beatles' She Loves You, with its repetitive lyrics, "She loves you, yeah, yeah, yeah" taking up nearly half of the song. And that too was a loud, obnoxious teen anthem in its time.
I'm also going to take this time to point out that She Loves You is a far superior song compared to Baby (or anything on the Billboard Hot 100 [at the moment]).
Now, I expect Biebermania to eventually die down, he will turn 13 one day after all (remember Aaron Carter? Of course you do/don't), and I expect auto-tuning your vocals to eventually be eclipsed by some new technology that wasn't invented to track whales or something (true story, Google it). But hell, you can't resist getting caught up in slightly enjoyable pop music, especially when its being handled by producers who have given us decent music experiences in the past.