She does not want her daughter to know too many things about the world, it's better if she stays ignorant and shallow, like Daisy tries to be sometimes.
Looking at Daisy's character, one can see she did care for Gatsby, though maybe not as much as she ended up caring for Tom.
Edit Daisy Fay was born in to a wealthy family in Louisville, Kentucky. Daisy, although ethereal in some qualities, is decidedly devilish in others. She ranked No. Or seems to be until Gatsby comes into play.
Jeanne Crain played Daisy in a episode of the television series Playhouse In reality, she is stuck in a marriage with her husband, Tom, who cheats on her with his mistress, Myrtle.