I wouldn't call it a trend, if by that you mean "something that's growing noticeably and is likely to become common"; I've seen it only sporadically. Calling a movement--meaning, some people are doing it, without specifying how many--is — is probably more accurate.
Where it came from philosophically is clear: from a desire to challenge stereotypes. Perhaps more interesting is where is it going--will — will it catch on?
As for "should be frowned on"--that's — that's an aesthetic/political judgement. I can't see a basis for rendering an academic answer to that.
