My problem with prophecy is that I'm a psychiatrist. I spend half my working life trying to convince people that nothing is preordained.
I see kids growing up in awful circumstances, sometimes depressed, who need to believe they control their own destiny.
I see families who are doing the wrong thing simply because their parents did it too.
The greatest weapon in my arsenel is the belief that people can choose to change any time they want to. They might need help to do it, but nothing is beyond someone who's motivated.
My personal philosophy of life is so opposite to the idea that things are preordained that I want my stories to be that way too, so this is the most personal of pet peeves.
I look on heroes who go questing because of a prophecy in roughly the same way as I'd view one who went questing because the mighty prince of some foreign country wanted to give him a great fortune for help smuggling the prince's personal fortune out of the country . . . after he'd sent a handler's fee of 10 000 gold pieces and his bank account details to the prince in an unmarked cave in the mountains.
Boy, that's a lot of ranting for one friday afternoon. It's definately been a ranty sort of week for me.