I, and I'm sure there are a number of people that fly this way, help fill up seats that were going to be empty by jumping on the planes at the last minute when a nice sale comes up. Once I got started with that, I stuck with the airline and started making more leisure travel specifically on that airline because that's where I had the status. Now I buy tickets for what I need and when I need to go, though I do go look for a decent deal.

If I hadn't been able to get status on some of the cheap tickets I started out buying, I doubt I'd have continued buying tickets and spending more as I do now. The hotels are a lot harder for me to hit status, and in general I don't have any loyalty to a hotel chain. I don't think I'd fly as often or stick to particular airlines if I hadn't earned and maintained status, since I do it as a voluntary leisure activity and not for business.

I can see the advantage to an airline having a dollar-based system, but I think the bonuses many of the airlines have implemented for more expensive classes of tickets address that issue pretty well.