Honestly, it wouldn't work, they can probably get away with adding one or two more FP attractions per park, at most. The problem is that if people aren't on a ride, at a show or in a line, then they have to go somewhere and there is limited space. The shops are already overcrowded, as are the counter service locations, the walkways are narrow, especially at Disneyland, so where do all of these people who used to be in lines suddenly go? There will be some that will go to other attractions of course, but overall that isn't what usually happens.
As for characters, FP for Princess Fantasy Fair could possibly work, but there really aren't any other permanent structures for character meet and greets besides Mickey's House and a FP there would take out the entire house. No, our character interactions are different and they need to be due to the demographics of who is in the parks.