Again, nobody is against IP integration.
Some of WDW's greatest rides were and are IP based. Current notable examples: Splash Mountain, Star Tours, and the Tower of Terror.
Nobody complains about these because they make thematic sense to their locations.
Splash is in the Frontierland area of the Magic Kingdom and retains the same aesthetic as the Country Bear Jamboree, while Star Tours and Tower of Terror exist in a park that was originally conceived as a working studio and celebration of movies and television.
The problem is in BAD IP integration. The folks who complain about Frozen in Norway are generally silent when it comes to the Three Caballeros in Mexico or Ratatouille in France, or the upcoming Mary Poppins attraction at the United Kingdom. Why?
Because the 3C's are actually touring across Mexico, and are seen animated over several actual locations in Mexico. It's still not a great ride, and a MAJOR downgrade from the original
El Rio Del Tiempo, but at least it DOES present the actual country.
Ratatouille? That movie actually takes place in Paris.
Frozen? The look of that movie was "inspired by" Norway, but it has absolutely nothing to do with the actual country of Norway.
Hell, 'Atlantis: The Lost Empire' would be a better thematic fit for Norway than Frozen simply because that movie, at least in the prologue, has actual Norwegian characters in it.
The only reason Frozen is there is because they wanted to get people and their dollars into World Showcase as quickly as possible.