Vlaakith became a lich for power alone. She drains the life force of her highest level minions to increase that power. That's why in older editions where the githyanki knights reached 16th level (or I think 10/10 fighter- mage in 2nd ED) before they could reach 17th level she'd sacrifice them to both get stronger herself and to ensure that none of her subjects could usurp her.. the way she usurped the ruler before her. I know she's not actually monitoring their levels, but that's what it said about her in either 2E or 3E.
I agree that Lae'zel has a naive view of her own people. Or she has an elevated position and believes that a dragon rider should defer to her even though she is not yet one herself. If I remember right they do have a caste system with nobility.
