Yeah, I don't agree with that. I don't think people should ask for gifts even. Giving a gift is the polite thing to do if you're attending a birthday party, but to ask for money in lieu if gifts just seems cheesy to me.
What do you think about parents asking other parents at school for money instead of gifts for their child's birthday present? (asking based on this news story: http://www.bbc.co.uk/news/uk-31147243)