Just my 2 cents on this matter.
I think on the merits of an arts degree as compared to many vocational degrees in developing thinking skills are pretty similar. I'm speaking as someone who has done two units of history and two units of philosophy as well as many units in engineering. I feel they've both taught me to think in different ways and developed my ability to think, almost everything you can say about an Arts degree is equally applicable to an engineering degree. I'm not pretending that my four units in the arts is equivalent to a whole degree, but I feel I've had a good taste of it.
The devaluation of the arts degree has nothing to do with a society declining in thinking, more so it's a cultural shift in the way we have entertainment. The great majority of us Australians are satisfied with Hollywood films and sport as our entertainment. This hasn't always been the case and I particularly recommend a German film named Faust on this, in which you have an insight into Nazi Germany and the people's appreciation for good theater and just how highly they regard Shakespeare, the only foreign playwright deemed un-bannable during the third reich. This is a culture (with many perilous ideals) that did value art and people wouldn't be satisfied with a trashy script with a few special effects to gloss it over. There was genuine demand from the people for theater, drama and fine art amongst other things.
There are many societies that have valued art to this extent, we're just not one of them currently. We, westerners, have seen something of a revolution in the sciences in the last few decades, with an appreciation for science that is growing steadily, we haven't quite had that cultural artistic awakening just yet where we move past Hollywood crap and society demands art, true art. I hope I live to see the day this happens, as I would much rather go see a well-performed Chekhovian play than some crap like Paranormal 4. When society demands theater, good literature (in electronic or paper form), people to teach their children history properly, art galleries and true live music (not Americanized bullshit but true music like jazz et al), then we will see an appreciation of the Arts degree.
Just because society has woken up as such, doesn't mean that Arts grads need to differentiate their degree on a pseudo-basis like 'it teaches us to think'. Most degrees teach you think, so please don't use this but it's not your fault society has woken up yet to recognize the merits of your skills.
Having said that, get over the Arts jokes and meme-pages, we engineers will continue to make them, learn to cop a bit of stick or give it back!