I'm pretty disturbed by how much objection is there that sounds like this: "He looks like a girl!"
Is there a problem with this? What's wrong with a guy who isn't big and strapping and masculine? You guys are making it sound like he needs a steroid dose and a lumberjack shirt and a beard just to be a real man. I like guys who look androgynous, and I know there are others out there who do (otherwise, there wouldn't be any fans of anime boys, ever, for one). I feel like this is one step away from criticizing tomboys for being too masculine and telling them to go put their dresses on and get back in the kitchen.
Also, oftentimes talent isn't enough to succeed. Whether or not he has any, complaining about people getting famous due to luck is pretty much spitting in the ocean and hoping you'll change something. Lots of famous writers are famous because some guy picked up their not-particularly-special book, happened to like it, and it spread everywhere. (Twilight, Eragon, I'm sure you can name a whole ton of these.)
If someone is famous, clearly they're doing something right, and objection to that shouldn't be directed at the artist -- but at the audience. If Justin Bieber has no talent, sings badly, can't write lyrics, and should by all logic not be liked, then you should really blame the audience for letting him have the time of day, not the artist for trying. He tried. Clearly people like him and his work, or he wouldn't be famous. So that says the audience is a bunch of philistines...but if the audience likes it, they do, and until you change them, he'll continue to dominate.
I think people hate him just because it's the Thing To Do and they have nothing better to hate on.