Primitive Christianity Revived, Again
I've worn a beard since the early 70s. It was a mark of nonconventionalism back then. Squares shaved, hippies (or freaks as we preferred to call ourselves) didn't. Some guys wanted beards but couldn't grow one. Poor saps.
I found that the look simply suited me. I began growing a full beard when I became plain. So I guess to that extent there is some meaning besides vanity. I never cared to shave my mustache, though.
Now that I'm grayer, I enjoy the Santa remarks from kids and play into it.
I wear a beard as often, facial features and the need to Trim or, have just the right 3'o'clock shadow, are vanities. An untrimmed beard avoids what might turn into a vanity for me. Also, plain Friends often eschew jewelry of any kind as frivolous, so a full grown beard indicated marriage. One can remove a wedding ring. If I came home with no beard, my wife would wonder who I was trying to impress. Finally, the beard is representative of plain dressed people everywhere, though beards are not part of any Quaker advices I know of outside of Fox's and Wilbur's exhortations that being "plain in appearance" is an integral part of the Friends witness.