Ah, but our fields are likely very different. If US were only offering the miles, I would decline. A mile a dollar would amount to nothing even at my pay from 5 years ago (which was onlyabout $25K a year, compared to about $19 if I still worked there). I could top up on gas with a Dividend Miles card and recieve the same amount of miles a year's work would. Plus the added hassle of redeeming and keeping track of miles would likely override my desire to travel. My neurotic friend in Boston just broke up with her boyfriend, is it worth all the drama to go up there and console/tackle a bottle of wine with her? Not if I'm redeeming a limited amount of miles, space positive or not. If there's an open seat, passenger or jumpseat, I'll hop on up there without worrying that I'm wasting a benefit I might need for something like a funeral. Especially when I could get a part time ground job with any other airline, that takes up very little of my time and provides me with traditional benefits on a major airline.
I'm poor. My free travel and unnatural interest in commercial aviation is the only thing that keeps me even remotely involved with the airlines. Sadly, I would venture that the same is true for people who are active. They certainly aren't there for the positive reinforcement, pay, or other benefits.