I figured since they bothered to show her making it that it would come into play at some point. Maybe not a big moment, but just some random moment where she starts to question where she is.
Maybe her using it is in a deleted scene, they could've maybe shown her use it on the plane or something (which would further cement the end of the movie being in "the real world") but, really, I think it was just there to show that she had made one. If we hadn't seen her make it we'd be asking why weren't show she had one.
I sort-of have to agree with a poster above who said Kitty Pryde's character was our "cabbage head" but all movies of this nature need one (that-is, a character who's a n00b to what is going on through which the audience learns what is going on by having the experienced characters explain to her. Ernie Hudson's "Winston" character plays the same function in the first Ghostbusters movie.)