I don't hate them.
They are an inoffensive boy band. What's to hate?
People hate them because they believe they cannot sing, which they can, and that they have been very lucky.
The fans defend them when there is a hateful comment on any of their videos (or anywhere) along the lines of 'why bother watching their video' which I would agree with. But, the fandom (which is bound to die down soon) are not as good at debating when it comes to Twitter, especially death threats.