Bumping because I love my 7mm-08.
As for the reason why it's not more popular, that has WAY more to do with culture and marketing than with the actual capacities/performance of the cartridge. As has been shown on this thread, the 7/08 is more than adequate for the vast majority of big game walking this planet. Moose, grizz, elk, plenty of large/dangerous African game, etc have all been capably put down with the "baby 7". I might want something bigger for an elephant, as if I could bring myself to shoot an elephant anyway, but I digress...
Shooting culture in the US throughout most of the 20th century suffered (yes, suffered) from an overdose of machismo and the rock-dumb "big animal need big bullet" and "you know it's strong 'cause it bruises my shoulder" patterns of caveman thinking. By the time folks started paying attention to the success folks in the nordic countries were having with the likes of the 6.5 swede and the few American hunters bold enough to take elk and moose with the 243 win, Hornady's very talented marketing department was coming out with the 6.5 Creedmoor and the rest, as they say, is history. Now we live in a split culture arguing with itself on Rokslide about which cartridge is "big enough" to hunt X Y or Z while continuing to under-emphasize actual practice and shot placement.
Anyway, all that's to say the 7mm-08 just came out at the wrong time, and unfortunately developed a reputation as a "girlfriend gun." I guarantee you that if, instead of Remington elevating it from wildcat status in 1980, Hornady had released it in 2007, spec'd it with a 1:8 twist and put the same marketing $$ behind it, it would have been every bit as popular as the 6.5 creed turned out to be.
[steps down from soapbox]
Happy Thursday everybody