Erotica isn't terribly easy to write either
No doubt you mean: Isn't easy to write WELL.

Sometimes I read a story that works as erotica but is merely a collection of favourite cliches written without talent or creative ideas. That's when it is easy to write!

I like to get a sense of the author's character, and what better way than through their humour. A little bit is philosophising or social comment is also quite acceptable to me within an erotic story.