I.e., the "war" between those with culture, and those without.

Always a tough call, followed immediately by accusations of elitism and snobbery.

A case could be (and probably has been) made that because those are the original paintings, with a great deal of provenance, and that advertising art has become "collectible", the prices paid are not out of line.

Personally, I have a big problem with the whole "collectible" phenomenon (I'm also not the only one I know who has suffered from the economic consequences of a spouse succumbing to the con). A collectible item's value on the market is utterly extrinsic, based solely on the amount someone else might be willing to pay for it at the moment. By itself, a Barbie doll (as a random example) is a worthless piece of crap, 11 inches of non-recyclable plastic and a couple of grams of polyester fabric. The same could be said for just about every nostalgic craze -- slide rules come to mind. In brief: "If you don't sell it, it ain't worth a dime, and you're still out the money you spent for it."

See also the Great Tulip Bubble (of which I first learned from a reprint of the 1841 classic, Extraordinary Popular Delusions and the Madness of Crowds; full text available here. "Tulipomania" is Chapter 3).

Thing is, "culture" always has been and always will be in the eyes of the beholder (not to mention his wallet). Sneer if you want, but the guy who sold those paintings is laughing, all the way....