Comic books are a business, and they compete in a purely commercial market. If people are buying lefty comix then writers and illustrators and publishers will attempt to serve that market. The same goes for news, movies, TV, music, you name it. People will alter their product to try and get customers, and any new market that starts to emerge will quickly attract those who wish to be first to exploit it. Although propagandists can alter a market, or even create new ones, by spending lots of money (after all, that is what advertising is all about) the common mythology as dictated by the business community is that free enterprise only gives the customer what he or she wants "no one puts a gun to their head..."). What works for SUVs, tobacco, and consumer electronics must also work for the popular arts. I.e, if comix are abandoning the traditional jingoistic model that worked so well in WWII and the Cold War that's because the customer is giving it up too.

The question you should be asking yourself is, why? You already concede that it is not an organized conspiracy, but some sort of sea-change that is occuring in the artistic/intellectual circles in society. But it would not be so successful if it didn't actually resonate with the average consumer of popular culture and entertainment, and if wasn't profitable because a market existed. The arts reflect what is going on in society, not the other way around.

The business/managerial class has always held the beret-heads in contempt. Maybe they should have paid more attention.