Now, this begs the question of how the Post-Modern era differs from Modernism. Is there any real difference between the two? Did we merely change labels for the sake of change? Did some cataclysmic even suddenly spell the end of one era and the birth of another? The answers seem to be, yes, yes, and no. Yes, there is a difference between the two, in appearances, of course...superficially at least...but mostly in philosophy. Everything that happened in the Modernist era since Manet through DeKooning was predicated on the romantic notion of the artist as an heroic explorer of the unknown, "bolding going where no man (or woman) had gone before".
Because Modernism had come to embrace so MUCH art history, it had reached it's capacity to define anything? So in answer to the second question, yes, change was needed for the sake of change.
And finally, no, quite the opposite in fact. It was a slow death and a painful birth. It must have been daunting for the DeKoonings and Klines to see the blood, sweat, and tears of their heroic efforts to blast art free of the last vestiges of representationalism become just another collected commodity with a price tag hanging from the frame. Here though, we come to grips with the most fundamental difference between the two eras. The artist of the Post Modern era today have not only come to accept the fact that they are "manufacturing" just another decorative commodity but to actually embrace the fact, emphasizing it, making snide comments about it, and perhaps even more important, not feel the least bit of remorse or guilt in cashing in on it. Whereas the old school WORRIED about "prostitution" the newborn pop artists who herald the advent of the Post-Modern era, GLORIFIED in every aspect of it.