Crossover (aka: park hopping) is a major reason Epcot doesn't have a parade. The daily strain on the monorail system and entry when people flocked to Epcot from their first park-of-choice for the afternoon and evening performance of Tapestry was an expense Disney simply didn't want. It short, a major spike, and couldn't be worked into the daily operations without vast over-staffing for the rest of the day.
Disney's solution? Eliminate the spike. They got rid of the parade despite it still being relatively popular at the time it closed. Yes it needed to be "redone" again to refresh it, but the MK parade has done that dozens of times without major changes at this point. Note that the same fireworks show that features the parade puppets still plays nightly.
So park-hopping can sometimes be a liability to Disney. Similarly, it was seen as a problem at the Disneyland Resort with World of Color - guests would start at Disneyland, run over to DCA for the World of Color, then run back to Disneyland for the rest of their night. Disney didn't want that type of touring pattern and the Electronica and such sprung up to try and keep guests in DCA after and before World of Color in the evenings. Dashing to Disneyland to see Fantasmic or the Fireworks was to be stopped.
Interesting, I always wondered why they got rid of the parade in Epcot.
Thanks.