I dated my wife for 3 years before I asked her to marry me. When we told her parents, her father, who I liked very much and I believe liked me, said to us "I don't remember anyone asking me about marrying my daughter". He wasn't angry but maybe a little disappointed. He WAS happy, but the traditional thing would have meant a lot to him. It's one of my regrets that I didn't ask for his blessing (which I'm certain would have been given). I think nowadays it's more about the parents "blessing" rather than permission. And it shows respect.