It isn't a surprise that people like writing about angels. I like writing about angels. But sometimes when I'm reading angel story descriptions (especially among the unpublished), there are some eyebrow-raisers:
- Angels are frightened that humans will find out they're real. I hate to break it to them, but all that talking to shepherds stuff outed them some time back. They tend to burst from the sky, glowing with holy light and singing. It's too late to decide they want to stay hidden.
And if someone isn't a believer, yet sees an angel, it's not like it's a bad thing. People have the warm fuzzies about angels. It's "ooh, an angel" not "argh, a giant tentacle monster". Out of all the worries an angel could have, this one isn't high on the list.
- Guardian angel falls in love with his charge. So an immortal angel watches a girl grow up. Then when she hits her teenaged years, and she's almost legal, uses his knowledge of her life to seduce her. This is portrayed as being highly romantic.
I realise I'm not the most romantic person out there, but am I the only one that finds that creepy?
- Angel has trouble learning to fly, so visits Earth. I don't know what it is about Earth that makes it easier to fly down here. Maybe Heaven has really high gravity. Maybe Earth has all the best angel flying schools. It's a mystery.
- Angels can turn humans into angels. There are various theories about angels. The religious view was they were all created in one batch, so there are never any new ones. A more modern view is that dead people can become angels. The idea of angels doing something to humans (other than murdering them) to make them angels is rather more recent... it usually involves swapping essences/souls/spirit pieces. There might be a way to write this without it screaming 'vampire', but most stories don't make it.
Most of these come down to the author going "vampires are so last year, but I want someone unattainable, immortal... aha, angels". Only without actually changing any of the vampire-specific things to angel-specific things (other than adding wings and a tendency to wear white)*.
Angels can be awesome in stories, but not when they're just feathery vampires.
* The learning to fly example is more specifically angelish, but is often an excuse to get the angel to Earth to have romances with teens, turn people into angels and worry that people will find out angels are real.