I've done a few MRs over the years but my motivation was not usually related to earning miles. It was related to earning status.
But I also *love* to fly. I'm probably in the lowest percentile of the traveling public that way, but I enjoy the airport experience. The in-flight experience (planes are awesome!). And the general buzz of travel.
And I almost always was doing a MR to somewhere I'd never been or someplace exotic (to me).
I can see how Doug doesn't value that business, but without MRs and the people interested in them he'd have far fewer online fans than he does. Think of the great trip report coverage he gets from all the blogs that show off his carrier's premium products. Air travel, despite being a near commodity, still has room for enthusiasm, style, prestige and romance. It's not the cable company, after all, unless the companies providing that service treat it as such.