It's popular for several reasons, for better or for worse. OK, definitely for worse. Feeling the push of curiosity myself, I asked my friends why they thought porno was so appealing to guys. After much grunting and some high-fives, they agreed. Nude women are amazing.
Women look great naked.
Naked guys just look like a bunch of spare human parts all stuck together. Simply put, guys are into porno because guys are into girls. But porno serves other purposes too. One is comedic value. Sometimes the most entertaining portions of a video are the opening and closing credits.