I'd been thinking about this since I read it and trying to come up with a reason why I liked Kasumi. Figured it out talking to her in my current playthrough just now: She's a people person. Not only is she pretty observant about people and incisive about their desires and stuff (like calling Kenneth and Gabby on making a good couple, even though they'd never see it for themselves), but she takes notice of literally everyone. I like that she comments on regular crew as often as the other squad members. Pretty much everyone else treats the crew as just nameless drones going about their work and ignores them altogether, but Kasumi notices the little things about them. Plus, she's the classic "thief with a heart of gold" archetype, which is usually pretty cool (see Robin Hood, White Collar, etc.).