My guess is that WOTC is learning from one of World of Warcraft's mistakes: they originally had no races in the "Horde" faction with attractive females, and as a result, the populations were incredibly skewed against that faction. Most women didn't want to roleplay an ugly female character, and most men who wanted to play women didn't either. Thus, when the first expansion came out, they made sure to add a "pretty" race for the Horde.
The upshot: if you want females of a race to be at all popular among players, you should at least give them the option of being attractive.
Now, there are some races (like orcs) where they SHOULD remain ugly for RP reasons. But for dwarves or githyanki... why not? (I'll use the dwarf example because I'm more familiar with the race, but I think it'd extend to githyanki as well.) Obviously dwarves think their women are sexy. As long as they're still obviously "dwarfy" (short and stocky), is there any harm in making them look non-ugly from the human perspective?