While I am not a fan of Newman, one thing I can say for certain is that it is easy to miss the point of an oil panting when looking at a flat picture of said painting. When I was young I did not get Miro. That all changed when I was able to see Blue ii in person. While I still expect people to criticize the painting for being simple, the actual painting moved me deeply and erased any thoughts that what Miro did was easy. Frankly it is harder to elicit emotion from a viewer with minimal tools than it is with realism. Paint a sappy scene that tugs at people's heart strings and you will get a reaction. This is the same reason there are so many songs about love and loss, it's easy to make people feel something they already have such a strong hold on. Try making someone feel something they can't put to words with only a few colors and no definitive iconography.
As for some of the fringe modern art pieces, there are pieces that were designed to make people question art and their perspective, to challenge the norms. Some of these pieces have value more for the discussions and questions they start than the quality or nature of the piece itself. Of course there are works that almost everyone finds trivial or overwrought in pretension but I do believe art to have a self correcting arc over time. Only those works that can impress someone 500 years from now, removed from social and time based context will truly live on. I love Duchamp's work for what it is but would never pay for such a piece. Those who do will own a piece of art history though, however ironic. I don't know of many people who consider his work to be the most important of any era but I'm sure someone does. As Cosmic pointed out, it goes a little deeper than just the piece.
Frozen, not sure what you are trying to say. You both admit that the highest end art auctions have little to do with art in general but you are the one who seemingly drew an inseparable relation between the two. Art as an investment is not the same as art in general. Just as buying wine as an investment will often diverge from what one may buy to drink. Art is hardly alone in that aspect. I give the high end buying of art zero relevance in my life and therefore it's irrelevant what happens in that realm. I certainly wouldn't judge the value of any work by its price and therefore would not conflate the two matrix's.