I draw the line at calling something art that is just essentially something anyone could do have put together in a few minutes without any skill.
i.e A black wall is not art.
Nor is a couple of colourful squares like this that is worth $70M:

Nor any of these paintings:
http://www.artsumo.com/blog/post/4
I don't know that this would be "worth" 70 megabucks. Still, the property of art is that it has both worth and value, only one of which has a monetary anchor attached. Not all "art" is worth a lot or very valuable, but some is. And it is not always that art which "laymen" appreciate. Still iguess art is worth whatever someone is willing to pay for it.
Just as a side note, i promise you Dave that you will not replicate that piece in a few minutes, if ever. Whatever anyone of us thinks it is worth, or not.
Liking something and valuing it or not, is a very subjective thing. In that respect one cannot be "wrong" in expressing one's opinion about - well - anything really, but art in this case.
In the classical art the artist attempts to capture reality as accurately as possible. From the archaic Egyptian stiffly posed figures the representative art has progressed via the greeks and romans to Renaissance and guys like Leonardo da Vinci and Sandro Botticelli to the medieval Dutch masters and their colleagues around the world. This kind of art is easy for everyone to appreciate and review: one can compare it to an attempt at photography using canvas or some other medium; maximal perceived realism was the target. In my opinion this culminates in the works of such artists as Michelangelo Buonarroti and others in Italy, Johannes Vermeer and Rembrandt van Rijn in the Netherlands, and others equally famous and talented - too numerous to iterate here. These are the artists you are "supposed" to appreciate.
The first deviation from maximal reality one can see in the works of the impressionists, expressionists, pointillists and what have you. Guys like Vincent van Gogh, Edouard Manet, Claude Monet, Camille Pissarro, Edgar Degas, Gustave Caillebotte, Marc Chagall, Georges Seurat and what have you. These guys started to create art where the main point was not hyper realism, but the feeling the viewer gets when examining the piece. Take say van Gogh's De sterrennacht (Starry Night) just to name one: What it represents is clear, but also it is clear that the depiciton is not realistic. Instead it evokes a feeling or impression. Nobody has ever suggested that this was because van Gogh was unable to create a better picture - instead it is obvious that this is the point of the whole work.
Then the scene evolves to guys like Pablo Picasso and cubism, by some considered the most important art movement of the 20th century and which is considerably removed from anything the eye can directly see around us. Similar in some respects is the art of Maurits C. Escher whose complex geometric fantasies are out of this world, representative though they are for the most part.
Latest at this stage we are starting to leave behind those whose imagination fails to see art as more than a brush operated camera.
With the evolution into non-representative art we start getting dismissals like the ones here - that "it is nothing, anyone can do it". Sure, not all art is immortal and lots of the cheap and cheerful "abstract art" is just trash. Especially that which is described in high-flying sentences of nonsense but void of any innovation.
Still, artists like Piet Mondrian, Vassily Kandinsky, Joan Miro and the many other abstractionists are just as much artists as anyone before them. They just explore a realm more removed from the everyday. Then there are those who present a harder nut to crack: Yves Klein and Marcel Duchamp come to mind. At this stage we are firmly where someone like Jackson Pollock neatly cleaves the audience in two - to those who appreciate him as innovator and those who think he just happened to accidentally kick the paint bucket.
Maybe what i am saying is that those who haven't studied or familiarized themselves with contemporary art should be allowed their opinion of it. But at the same time the opinion may not be worth a whole lot. After all, opinions are like buttholes; everybody has one.