The Poor, the Marginalized, the Outcast, the... Shepherd?

I reflected on something listening to the readings this morning, not for the first time.
I'm sure everyone has heard the standard Christmas sermon more than once, the one where the shepherds play a large, heart-tuggin part.
"Isn't it remarkable," says Father, "that the angel firt gives the glad tidings to the lowliest of the lowly, the shepherds. Shepherds was despised by decent people in the first century, they were not allowed -"

Wait a minute.
David was a shepherd.
Abraham was a shepherd.

God promises, over and over again in the Old Testament, to send a Shepherd to govern His people! was He thus threatening to shame them?

Or, despite what The First Nowell says, are sermonizers making too much of the poverty of the shepherds the better to preach on the purported "preferential option for the poor"?

(Exodus, of course, instructs the chosen people NOT to "favor the poor in a lawsuit".)