Why do they never listen

A little digression from my usual virtual Middle-Earth posts: I was reading The Children of Hurin and i couldn't help but wonder... why do they never listen?

I mean, there is Melian, a Maya gifted with foresight, and a true one as well. Everyone knows that: people from the Hurin's House, because they've always been close to Elves of Doriath, and especially elves of Doriath to whom Melian is a queen.

But hell, no! Everyone always knows better than her. She tells Turin not to leave the Girdle or his course will catch up with him... he does. She urges Morwen to hide from Morgoth into the Girdle, she refuses. Than she asks not to leave the Girdle as it would be Morgoth's design (actually, she confirms Morwen's words that it is Morgoth's design), she still does.

And so on, and so forth.

But those are all stupid mortals, and there is still Beleg, high among the elves of Doriath, Melian's subject who, after all those hundrets of years, should be aware of her powers. And still, she tells Beleg, don't take that sword or it will be your doom, but he literally answers 'I'll take it anyway'!

If I was her, I'd throw a fiery hissy fit at all those annoying losers...