MK feels much more oppressively crowded then the other parks not only because the crowds are larger but because it’s much more tightly packed and there are far fewer open “vistas” (I don’t have the design language to be more precise), spaces you can look that aren’t packed with people or structures. EPCOT in particular is arranged to accentuate these open spaces (one reason the overly busy new hub fails) but MGM and AK have them too. The Frontierland changes will not only increase crowds but, by getting rid of the parks only remaining vista, will increase the SENSE of the being crowded.
To put it simply - MK badly needs more open spaces, not fewer.