We don't know what kind of pixie dust Lucinda's been snorting, but she's a delusional and ditzy excuse for a fairy. Okay, we kind of thought that all fairies were like this, but evidently not: Mandy disparagingly says that "Lucinda is the only one who's rude enough and stupid enough" to use big magic like flashy disappearances in front of normal humans (4.19).
Ella's not the only one to suffer thanks to Lucinda. Her gifts are majorly dumb, the whole reason re-gifting was invented. Unfortunately, you can't re-gift a curse. Take the giants, whose wedding Ella attends: they're not at all happy with the gift Lucinda gave them: being together always. Seriously, can you even think of a better way to get sick of someone?
For all her stupidity and stubbornness, Lucinda is a notable character because she changes and evolves as a person—er, fairy. When Mandy tricks her into experiencing the kind of obedience curse she gave Ella, Lucinda realizes that maybe she should hand out "blessings" so casually.
Lucinda swears off doing big magic, which means she can't remove the curse on Ella—but she can perform small magic to help Ella get to the ball. In the end, Lucinda becomes a lot more like a good fairy godmother than an evil witch. Yay, Lucinda!