Lotro continues to deny players the chance to play as female dwarves. This can supported by the rarity of female dwarves, but there are heaps of precedence within  the game for lore being circumvented to create a good game. 

1. Hobbits are known to keep to the shire, and many folk outside of Eriador have never even heard of a Hobbit. Even so, Hobbits have been accessible as player characters since the game's inception. No one bats an eye when a Hobbit ventures into the depths of Mordath, or into the Grey Mountains.

2. Beornings are even rarer than Hobbits, and are known to only rarely venture from their home in the vales of Anduin. Once again, they're playable characters which are rarely remarked to be an oddity by any characters within the game.

3. Some of the classes take great liberty with the nature of magic in Tolkien's world. Tolkien explicitly stated in his lifetime  "that it is not to be come by by 'lore' or spells; but it is an inherent power not possessed or attainable by Men as such." The Loremaster and Runekeeper both violate the nature of magic in Arda when strictly interpreted through the literary canon

I don't bring these examples forward to disparage the game, or shame the developers for these features. I love Lotro, and the loremaster is my favorite class. However I believe that the existence of these features ingame alongside the absence of female dwarves show a degree of uneven application of theory. Female Dwarves should not be excluded from the game simply based on their rarity within the world.