Herbivorous males.
Also, consider the demographic most anime is aimed at: Teen-Young adult nerdy males. I don't know about you, but as a teen I was
terrible with women(in fact I'm still terrible...), and so a lot of clichés in Anime had a certain amount of resonance. Also, seeing guys fail at romance like that has a certain element of Schadenfreude.
So the typical romantic/harem plot, whereby the loser male gets all these girls holds a lot of attraction to otaku, who may be losers themselves. It tells them "You can get a girlfriend too!".
It's as much a case of a demographic being catered to, that in the west does not get catered to. Closest thing might be Judd Apatow movies.
Also, in a society where males are dominant, there's a certain comedy in males being subservient. Consider American Family Sitcoms as well. Going back to the 30s the father is usually somewhat of a doofus, with the wife is smart. This is drawing comedy by basically flipping traditional gender norms.
For instance guy abuses a girl -> drama. Girl abuses a guy -> comedy.