Mileage running arguably makes sense for some travelers, that is, the sort of people who don’t mind spending a weekend on airplanes going nowhere in particular.
That sounds like a blast - NOT.
These people have a well-established subculture; the Mileage Run forum on FlyerTalk, an online travel discussion board, has generated more than 24,000 threads. But mileage running has never made much economic sense for the airlines. The purpose of a frequent flier program is to build loyalty and retain customers who generate a lot of profits. Mileage runners aim to buy tickets with the lowest cost per mile and extract as many points as possible from them; this is not high-margin behavior the airlines should want to encourage.
And increasingly, they aren’t.
Good riddance. Sounds like we’re closing a loop-hole that should have been closed a while back. Now I can rest assured that all those breathing the refined first-class cabin air with me have at least paid for the privilege - not just gotten their seat because they booked a cheap round-the-world-and-back-going-nowhere-cause-I’m-in-it-for-the miles flight or two. :-)