Why didn't they use the same dress Elsa was wearing at the very end of the season 3 finale for this season?

I really liked that dress. It didn't look exactly like the film's version of it like the current one does but it looks more fancy and creative and cool and it might've been cool to see Elsa wear a slightly different version of her ice queen dress. I do like the current dress but like someone else said one time, it kinda looks like something from a con convention like comic con or something.