it is quite well explained in pg' blub language text. The reason to learn haskell is twofold : make you a better programmer (functional programming breds good habits in any language and help you think differently about problems), learn something interesting (puzzle your brain for the pleasure of solving the puzzle).
It's going to take me months of my spare time to really get Haskell. I've got a lot going on in my life; I've got plenty of other uses for that time. If I'm going to use that time to learn Haskell, I want to know that the payoff is going to be there.
And saying "once you learn it, you will become enlightened", as if Haskell were Zen Buddhism and the benefits cannot be rationally discussed, well, that's not a very useful reply.
On the other hand, trying to explain to people the benefits of something they don't understand is really hard, because they don't understand it well enough to understand the benefits.
I think a big part of the OP's attitude might be in response to the attitude of a number of Haskell adherents: Our language is the greatest, and if you don't get why, it's because you're ignorant. If you've looked into Haskell and still don't get it, then you must not be bright enough to see the greatness of Haskell.
I exaggerate, but only a little. That kind of attitude makes the non-Haskell people resent the Haskell crowd, even if it's only a minority of the Haskell crowd that reeks of arrogance.
[Edit: I should state more strongly that the arrogant types are by far the minority, especially on HN.]