In the commercial art world, a lot of what you see is impressionism. Almost every major museum show is on impressionism. Why? It sells? Why does it sell? When the movement started it was breaking the rules for what "Fine or Classical Art" galleries wanted to display for artwork. Through time and especially now, this work is iconoclastic. That is, the impressionist artists define culture today, in fact the images define "Fine Art" today because the work is easy to read, that is easy to appreciate and easy to enjoy.
I think the colors are the first reason this art is easy to approach. Color is the first barrier to enticing the viewer (my opinion) it talks to our senses first. If you hate a color you move on. Not just color but the combinations of the colors, the pallets, are wonderful. They are often bright and varied.
In my mind, the current popularity of I. Art is due to the "Modern Art" movement."Modern Art" of the last century was often abstract or so out of the box it would weird the unsophisticated viewer out and it would alienate many. That was the point of a lot of it. It was to be "out of the box", "outside the lines", and to have "shock value". I. Art gave people who wanted to understand art and appreciate art an easy out. They could have quality images that were considered good art. In certain cirlcles art is like bread, and wine, and fresh flowers; it is a must. So, for those that hated the modern stuff, they could still be artsy fartsy and have good art. People who collect art can read volumes from reading into another's collection.
Lastly, the I. art movement reflected the rebelliousness of its time. I believe that that was appealing to collecters who were living through the radical changes of the 20th century.
