I'm one of the biggest critics of exposed showbuildings but Gringott's doesn't really bother me. For one, it's in Universal Studios, and I'm all for preserving the studio theme of the good ole days (yes, even if that means boring soundstages everywhere lol). Second, it doesn't really take away from anything. It'll only be visible from outside Diagon Alley, and if you're outside Diagon Alley, what difference does it make if you can see the showbuilding or not? Inside the area, yes, you want to be enveloped in the theming of the wizarding world and for it to be easy to believe that that's really Gringott's you're inside and not some warehouse. But outside the area what difference does it make? Once you aren't in it anymore there's nothing to be immersed in, nothing that doesn't already make you realize it's not just a theme park ride in a plain old building.
The FJ showbuilding is different because it immediately takes you out of the theming of WWOHP and Jurassic Park. Gringotts will take you out of the theming of what? Fear Factor??
I think it'll all be fine in the end.