M.H.
yep, that crib is a safe ,comfortable place. It sounds more like she doesn't want the new freedom... but rather is scared of the change.
My son was ousted from his crib at 17months.... pending the arrival of his younger brother and sister....
We would first read books while sitting in that new bed..... then worked up to naptime. We let him play in and around it for a good month before really expecting him to sleep in it...
I also put glow-in-the-dark-stars around the bed, to make it more interesting. We also picked his favorite character for the new sheets and comforter.
I would think "reasoning with her" is not the answer... but rather some sort of reverse psychology has better chances of success.....
Maybe have her help you dismantle the crib and put it in a box to give away to a new baby or whatever story you come up with.... something that makes her feel good about letting it go.... good luck.