Why do people like full-of-hate celebrities?

Jeremy Clarkson. Jeremy Kyle. Simon Cowell. Both the Hitchens brothers. Frankie Boyle.

What do they all have in common?
They all have the benefit of immense media attention, a large fan base, and the status of "celebrity", and they have all earnt it by being angry, bitchy, rant-filled, and in a number of cases, hateful.

Why are we, the public, so attracted to icons who unleash anger and aggravated criticism unto the the world? What do we get from watching these people rant and rave about various aspects of reality, often disproportionately to the actual negative attributes of the subject of their anger?

Part of the reason, it seems to be, is the rather pessimistic stance which many of take that you can only be sure that someone it being honest if they are being negative. This does actually make a lot of sense- there are a lot of reasons why someone would pretend to be positive about something (courtesy, to build rapport, to appear nice, to get a promotion and/or free stuff), but there are no obvious reasons why someone would be untruthfully negative. Therefore, the only reason someone can have for being negative is that that is what they genuinely think.
However; this argument is self-destroying. Because we have attached so much respect to open negativity, both in the media and in social contexts, there is now a very clear vested interest for people to bitch and criticise untruthfully. I had a friend in secondary school who would intellectually complain about anything and everything which he had the opportunity to- yet it was obvious that he didn't actually give a flying monkeys about half the things he was going on about. He just understood that if he was negative about things, he would be associated with attributes such as intelligence, insight and, perhaps above all, honesty. (I know, the irony is killing me too.) And I am sure that this is happening with TV personalities, journalists. orators etc.

The other reason is, quite frankly, that is makes us feel better about ourselves. As humans, we think negative thoughts every day. But the dang thing around us called "society" tells us that we need to avoid expressing these thoughts vocally, because as members of society, we need to ensure we don't make other people miserable.
Seeing celebrities bitch and moan lowers the bar for how much negative expression is acceptable. In it's simplest form, the argument goes "lots of people on the TV are doing it, therefore it's okay for me, too". And so we are able to whine away about more and more of the inconvenient or unsavoury things in our lives, and as a result, we feel better about ourselves. We are releasing our negative thoughts in an effective way, and we can no longer be seen as bad people for doing it. If it does end up making other people bored and miserable, so what? It's not our problem. The media said it's okay to moan, and these people we're talking to should catch up to that.
This, of course, is a bad thing. As humans, we are blessed with a remarkable capacity of judgement and understanding, and are quite capable of weighing up the benefits of unreservedly getting stuff off our chests with the consequences of bringing down and alienating the people we're talking to. Setting our values by the bar set by the media is lazy and unhelpful.

As an overview; negative opinions are neither a good thing or a bad thing, they are just a fact of life. We shouldn't condemn others, or feel guilty ourselves, for complaining about something once in a while; but neither should we exalt those we are constantly critical of nearly everything.