Don't women grow beards all the time?
In all seriousness, I think the developers were too lazy (or simply didn't have enough resources) to create female avatars for some of the races, so they just reused the male ones.
Also, in some fantasy lore (don't know if this applies to the Baldur's Gate universe), female dwarves do have beards. I know that, in, for example, at least one version of Final Fantasy 4, there's a dwarf who mentions their mother's beard.
Does either the BG universe or the Forgotten Realms setting specify whether dwarf women have beards?
Edit: Reworked first sentence, because I didn't like the original version.
Post edited February 13, 2018 by dtgreene