None of that makes her evil though.
Heck, you can literally use the same description for humans IRL. Does that make every human inherently evil? Are YOU evil?
Lae'zel shows time and again, she is significantly less "Evil" than others of her race. Literally, from the moment you meet her and she DOESN'T just cut you down where you stand.
Laezel is evil because of her upbringing, that she believes in and follows at the time you meet her on game. If you insist on comparing the githyanki to humans, then frankly they share similarities with fascism; the same military nationalism, belief in their own supremacy, disregard for others and xenophobia.
That Laezel does not murder you where you stand is a pretty low bar, btw. She does not so out of sympathy, but because she needs you to even have a chance to make it to the creche, something she is aware of. And indeed she is right, because if you do not recruit her she ends up dead. Not that different from Voss who changes his approach completely once you have something (or rather someone) he needs. But the non-gith that are of no interest to him? He just points his dragon their way.
I'm not sure where you got the idea that githyanki always kill on sight. You could interact with some of them without bloodshed even in original BG2.
The issue with Laezel's writing is that her quest is tied to Orpheus, who is practically a non-entity throughout the game. This revolution of theirs is based on Orpheus' claim to the throne, but the problem is this claim is through Gith herself, who was the one who put gith on the path of conquest in the first place, causing the split with githzerai. So at this point the important question would be: does he intend to follow in his mother's footsteps? Or does he intend going against Gith's own ideas? Which could have been an interesting concept to explore, if Larian actually gave the guy some screen time before the ending.
But they don't, and so Laezel's quest is about turning away from Vlaakith, only to start following Orpheus instead, the guy you know less about than Vlaakith.