Tolkigen skrev:
små skäggiga dvärgar
Även de kvinnliga dvärgarna hade förmodligen skägg.

Så här säger Tolkien i appendix A.
Citera:
Dís was the daughter of Thráin II. She is the only dwarf-woman named in these histories. It was said by Gimli that there are few dwarf-women, probably no more than a third of the whole people. They seldom walk abroad except at great need. They are in voice and appearance, and in garb if they must go on a journey, so like to the dwarf-men that the eyes and ears of other peoples cannot tell them apart. This has given rise to the foolish opinion among Men that there are no dwarf-women, and that the Dwarves 'grow out of stone'.
It is because of the fewness of women among them that the kind of the Dwarves increases slowly, and is in peril when they have no secure dwellings. For Dwarves take only one wife or husband each in their lives, and are jealous, as in all matters of their rights. The number of dwarf-men that marry is actually less than one-third. For not all the women take husbands: some desire none; some desire one that they cannot get, and so will have no other. As for the men, very many also do not desire marriage, being engrossed in their crafts.
Enligt
The Peoples of Middle-earth (
HoMe 12) så stod det i ett tidigare utkast (och även i en tidigare version av
Silmarillion) uttryckligen att de hade skägg. Personligen tror jag att alla dvärgar i Midgård föddes med skägg.
Anledningen till att Tolkien namnger Dís i
LotR är förmodligen att hon omtalas redan i
The Hobbit men då inte nämns vid namn: "Fili and Kili had fallen defending him [Thorin] with shield and body, for he was their mother's elder brother". Men läsare av
Bilbo missar detta då Hallqvist strukit "for he was their mother's elder brother".
Det är frestande att som Jackson hitta på andra förklaringar än den uppenbara även vad gäller orker. En hyfsad sammanfattning av vad som brukar sägas i frågan finns
här.
Och visst, det här säger en del om Tolkiens perspektiv. Fast det viktigaste med ett skönlitterärt verk kanske inte är att alltid vara helt politiskt korrekt (långt in i framtiden).