Me, because I can't publish contemporary fiction under a name that people would associate with fantasy...certainly not erotica-esque stuff even if the fantasy does have spice. Also people of a younger age (but still adult) might read my fantasy stuff and not like the more "spicy" stuff I write under a different name.

I do! One of my pen names has heavy spice (this one) The other does not- it’s poetry and the occasional middle-grade fantasy novel. Didn’t want any wires crossing on accident for readers!