Why You Gotta Be So Rude?

It can be a nice gesture (I have three married siblings, and my brother-in-law did ask my dad for permission before proposing, which was a touching little token of respect), but I don't think it's really of any importance or that it would be disrespectful not to ask the father. Adults can do whatever they want without parental permission, marriage included. I doubt that I'll ask the father if I ever reach that point, both because it would be awkward for the girl if she turned me down and Daddy asked her about it a day or two after, and because I'll probably be too nervous to care about much of anything besides her answer. And yeah, it is rude (unless the guy's genuinely a bad person), and kind of pointless - it's not as though the person will go "Oh, that's fine, I won't marry her if you don't approve. Guess I'll get going then."

I think simply meeting the parents while within the early stages is a good enough gesture, so you at least give a good impression onto them.