This is actually a very interesting question, IMO.

If you are comparing it with the cheapest way to get from point A to point B, it clearly is no bargain. However, that is not the comparison I make. For better or worse, I have gotten myself hooked on premium class travel and cannot go back to Y except on short flights. OWEs get me into the premium cabins (I AONEs, BTW) for, what for me, is an affordable price. For what I pay for my AONEs, I maybe could find a round trip F fare, probably on a second tier carrier, but that would be it. With the the AONE, for the same price, I can get an entire year of travel and can get either to or reasonably close to, anywhere in the world I want to go. While I take mileage into consideration when planning a route, I first consider where I want to go. Since I am a leisure-only flyer (for the moment, at least), I pick where I want to go and then devise a routing that maximizes the mileage. I would not avoid a place that I wanted to go to maximize mileage, but I will add cities that that I may not have considered top of my list to maximize miles (for example, doing a RT HKG-NRT-HKG turn or a RT from JFK to the Carribbean). Also, the miles I earn from one AONE are enough for two First Class award tickets, which covers most of my leisure travel for the next year. In other words, i get two years of travel value out of one AONE ticket. I am doing one this year, will use the miles I earned next year and do another AONE in 2006.

Most importantly, it is fun. I enjoy the entire flying experience and with an AONE ticket, I can maximize the pleasure of the experience.