Idiot Premise: Played for Laughs. Both Alan and his guests regularly loathe each other and are unwilling to play along with the others' gimmicks, leaving wonder to why any of them agreed to appear on Alan's show in the first place.
Let's face it, almost any guest that isn't as big a swine as Alan doesn't deserve what they go through on the show.
The scene in the Christmas Episode where Alan desperately begs Tony Hayers not to cancel his show and brings up the fact that his wife left him on Christmas Day does help the viewer feel momentarily sorry for him, since it's one of the clearest insights into how desperately unhappy and lonely he is deep down. Of course, the fact that he's also going around punching people with a bird stuck on his fist might temper some of this sympathy.