It's not about productivity. Humanity could spend these 14,526 years listening to J.S. Bach, a genius whose talent found no match in the human history and yet dedicated as much as humanly possible of his life to music.
That said, Gagnam style brought a smile to my face and added a bounce to my step; there's room for many things in culture and not all time is wasted, even "downtime". I'm sure Bach took breaks too.
Gangnam Style is brilliant. You can watch it dozens of times, always discovering something new. It also spawned a large number of extremely entertaining spoofs.
It would indeed be a sad world if we had peaked culturally at Bach. Fortunately, we haven't.
The terms arrogance and pretense were used for a reason.