I do take exception to your contention it was overrated, however. Despite being the #3 grossing film in 2013, its reviews were average to above average; its Rotten Tomatoes score is 89%, and the user score is 86% (these results are pretty middle-of-the-pack). As such, I would say that most people have a realistic view of the artistic and technical merits of Frozen. Hardly overrated.
I suspect there were more intangible qualities that helped it become the phenomenon that it did: strong female protagonists, identification with Elsa's sense of alienation, family bonds and unconditional love, sacrifice. Regardless, whatever caused Frozen to resonate with so many people is not invalidated simply because you don't understand (or disagree with) its popularity.