IPs are fine. They are needed and have always been a part of the parks. The characters too have always been there. In 1955 Walt had Dumbo, Snow White, Mr. Toad, Peter Pan, Casey Jr. (Dumbo), Mad Tea Party and such as opening day rides. Alice in Wonderland came in 1958. That is all of Fantasyland, and even Sleeping Beauty Castle was technically an IP with an upcoming movie. Swiss Family Treehouse was an IP by the time it opened in WDW in 1971. Heck, even Splash Mountain is an IP.
However..............you have to balance both. Those are great attractions but there has to be imagination too. You need the best of both worlds. Look at all of the stuff from the brain of Walt:
Jungle Cruise, Pirates, Haunted Mansion (in the early stages), Country Bear Jamboree (early stages), Tiki Birds, Carousel of Progress, Mr. Lincoln, Small World, Railroad, Autopia, etc.
Then stuff after the fact like Tom Sawyer Island, Space Mountain, Thunder Mountain, Hall of Presidents, etc.
You need to have the best of both worlds, that is what makes the park great. Without it then there isn't any true imagination as far as I am concerned. Expedition Everest opening over a decade ago shouldn't cut it as the last true original ride.