You can’t browse through the Paranormal Fiction section of a bookseller without running into something with an angel on the cover. There are whole sub-genres devoted to romance between angels, romance between angels and demons, romance between angels and humans, angels and vampires (!), etc. If there’s a supernatural creature out there, someone, somewhere, is going to want to have sex with it. Or write about someone having sex with it.
This is not to disparage the genre: people like what they like.
Call me a purist, but if you take a thing too far away from its essential nature, it ceases to be that thing and becomes something different. If obedience to God is an integral part of an angel’s being, then it will cease to be an angel when it defies God. Without God, an angel is no longer an angel.
The idea of angels acting in defiance of an absentee God is all over modern fiction, particularly the TV show Supernatural. In an increasingly secularized media culture, this divorce of angels from religion, from God Himself, simply turns angels into superheroes. X-Men. Beautiful, winged X-Men, but mutants all the same. They can fly around, have super-strength, perform miracles, but lack the thing that makes them actually angels: faith in and obedience to God.
The angelic fiction sub-genre has plenty of room for latitude. If there are sparkly vampires and Teen Wolves, there can be superhero angels. A fallen angel doesn’t have to de facto become a demon, an idea I explore for the Watcher angels in The Blessed Man and the Witch.
Nevertheless, magical powers and feathered wings do not an angel make. Secularizing an angel takes him away from his core and transforms him into a superhero.