Except here's how the math works. Last year there were an estimated 18.5 million people through the MK gates, which is about 51,000 people a day (up 13,000 a day from 2004). A 4% increase on that is an additional 2100 people a day. You'd think 2100 extra people would be easy to absorb, but there are limitations on ride capacity; it takes the same amount of time to load and unload people during each ride -- if you figure those 2100 people are there for 10 hours, and they go on the Disney average of ten rides (actually it's nine, but that math is harder) then you're adding 21 people an hour to each ride. If you figure each rider takes about 90 seconds, you're adding 30 minutes to each ride.
It's not FP+ or the lack of FP-. It's the people in the park that's at the root of the problem. Because the lines are universally longer, people try to come up with different strategies -- EHM, rope drop, coming at times that used to be slower. There re 30,000 rooms at WDW -- that translates to 100,000 people guest on any give day. If they split the way they traditionally have -- 35 percent at MK, then that's 35,000 people just from the resorts. 35,000 people competing for the same fast passes and ADRs. Everything seems a lot more crowded because it's a lot more crowded, and that will probably remain the norm, no matter what crowd management system they use.