I have this same gripe (about HN too, I suppose). Flickr claims that it's a philosophical thing - that URLs shouldn't change, so the username I chose when I fir

I have this same gripe (about HN too, I suppose). Flickr claims that it's a philosophical thing - that URLs shouldn't change, so the username I chose when I first registered years ago should invariably be what I'm associated with for the rest of my life. They likely do have the technical ability - when you initially register, your URL is represented by internal IDs (like 1234567@Z01), and you then choose your 'friendly' url. So it doesn't seem like a stretch that they could extend this to allow changes.