Art doesn't always have to be angsty to be considered True Art. Indeed, many great works of art are quite pleasant in tone. Happy even. But if it crosses the line from happy to amusing, or even—god forbid—funny then all bets are off. A serious artist is required to be serious if he expects to be taken seriously by serious art buffs to whom seriousness is Serious Business. Compare to Comedy Ghetto, which is about comedy media being taken less seriously in general, and "Stop Having Fun" Guys, which is when a similar aditude is applied to video games (a medium intended to be fun).
Hello, Unknown Troper. You'll need to get known to lend a hand here.