Well, I have several reasons for preferring novelettes:
1) When I read erotica, I want an engaging story with good characters and a little backstory but not a lot of useless details. (Basically, I want to get hot in a short amount of time.) I've read erotic novels before and had to sift through some boring sections to get to the good stuff.
2) For me erotica like a poem, concise and to the point.
4) I have a short attention span. These days I prefer reading shorter stories, so it only makes sense that I also enjoy writing them.
6) Besides, the word "novelette" just sounds cute and sexy. Don't you think? ;)
The simple answer to why Red Phoenix writes novelettes:
She likes it that way.
I hope you do, too.