I think she makes a lot of sense actually (as for looks, Ken Levine has stated she is older in BAS than Infinite Prime) once you think about the life she has lived.
In the fan theory on Wordpress, Ballbuster Elizabeth: Why Burial at Sea makes sense, I think the author makes a great point:
I like Elizabeth, but she is not a paragon of forgiveness and saint-like kindness. (Remember Lady Comstock?)
In other words, she’s a real (make-believe) human being, and I don’t know about you, but as a real human being too I would be extremely pissed off.
They make a great point: Elizabeth doesn’t forgive easily. Hell, I was kind of pissed off at her during the whole Lady Comstock ordeal because I didn’t understand why any of this was Lady Comstock’s fault. I mean, they find Lady Comstock’s diary in Slate’s locker and it flat out says that Elizabeth is not her daughter. As far as she was aware, Elizabeth was the result of Comstock’s infidelity… so wouldn’t it be a bit understandable that she wouldn’t accept Elizabeth as her daughter?
Anyway, that’s another discussion for another time. The other thing I liked about this article was the final quote:
We met Elizabeth when she was young, sheltered and innocent. (And adorable.) She didn’t even know she was the Lamb of Columbia or that Comstock was supposed to be her father. Elizabeth in BaS knows everything. Elizabeth in BaS isn’t Elizabeth from the tower because Elizabeth has finally had to grow up.
And I agree. Starting at the end of BioShock: Infinite, Elizabeth is forced to grow up, but sadly (in my opinion, she grows up looking for revenge at any cost.