1) In the Guide to the Astral Plane, the githyanki are portrayed as an egalitarian society (i.e., neither males nor females are oppressed; both genders have equality of opportunity). If this is the case, why has every Githyanki monarch (that we know of) been female? What aspect of their culture would prevent a male githyanki from taking over, particularly after the demise of the lich-queen?
2) In the same guide, it's indicated that githyanki have neither families nor hereditary social classes (eggs are laid, hatched, and hatchlings are brought up in a communal setting). It doesn't matter one bit if your mom/dad is the supreme leader of the city. How does the idea of a hereditary monarchy persist in this society?
Sticky Wickets
1) Tradition. The queen is female simply because Gith was, and Vlaakith I was. Nothing prevents male rulers, but since traditonally the githyanki have been ruled by a queen, not a king, they are much more likely to accept the former.
2) Yea, that always irked me too. Perhaps it is a monarchy, but not a hereditary monarchy in our understanding of the word. I figure (and this is just me, better bashers than I know much more about canon) that each queen chose her successor (or potential successor, many queens outlived their first few chosen) to take up the mantle of Vlaakith should she die. Hence the current chaos, because Vlaakith CLVII did not have an (unconsumed) successor chosen and ready to step into the office of queen.