I don't that many people hate Loreen as an artist. Sure, we're a lot who find it way too overrated, but I believe the actual reason why so many people are against it should be found elsewhere.
The thing is that the human nature wants underdogs to succeed. We want the unexpected to happen, we want the dark horse who against all odds manages to beat the giant. Sweden has gained a reputation that makes them a country with a large following, but what one shouldn't forget is that massive hype and an almost godly achieved status, also generate haters. Sweden's role every year, regardless of their entry, will always be a top-fave for the victory. This obviously pisses off a lot people and rightly so because this year it has just...escalated.
Almost no matter which country who dare threat Sweden at the top tonight, it is going to be the modern version of David vs. Goliath, and I personally can't wait to see who wins it.