How much Monsters Inc. merch have your friends purchased in the last 5 years? How many times have they seen the movies in the past 5 years?
There is a difference between being a "liked" IP and being a popular IP. No question that Monsters Inc. is universally liked, but that doesn't make it popular or relevant.
RNR is super popular, not because there are so many Aerosmith fans out there, but because it is E-Ticket. This will be the same thing. They could have themed this to Darkwing Duck and it still would generate the same excitement, not because people love the IP, but because people want a thrill ride and something new.
It's just silly to say that because it's Monsters Inc. this is new land is going to be wildly popular. It's going to be popular, because it's in a park that desperately needs attractions.