Delta introduced a revenue component to their Skymiles program - that probably is partially aimed at reducing the loopholes of MR/TP runs. Not sure if its working or not, but for 2015 they are raising the threshold again. To be their top tier Diamond you need to spend $15k + either meet the Mileage or segment qualification. I think many existing Diamonds/Platinum's etc. don't like it of course since the US domestic traveler can rack lots of miles and segments on cheap tickets. Again don't know whether the program has been successful from Delta POV or indeed from those left in the top tiers as the ranks are presumably thinning out as the lower $ value members are weeded out.

Personally I don't get too hung up about it. If someone wants to spend their weekend flying from BRU - HNL with a bunch of stopovers in-between only to get there only to turn around within 24hrs then they deserve to sample the good life of being a GCH or GGL. In reality its not that different especially when you land at LHR it makes next to no difference in getting through the shambles at T5 :-)