Forgive me, I must have misinterpreted when you suggested "a connective narrative across all Disney Parks" to mean the parks themselves. Having said that, I really don't think all the Jungle Cruises across the world need to be "linked together" as you say, any more than they already are by proxy of being, well, Jungle Cruises.
If, from their inception they had been designed at the same time as JC1, JC2, JC3, etc where, when combined, they helped tell a larger narrative, that would be one thing. But they weren't, and I think Disney is trying too hard to retcon in these "connective narratives" and acting like it was always meant to be that way. (Pixar Theory anyone?) Not everyone will have the luxury of visiting every Park across the globe, so bottom line, they need to be focusing on making each individual experience the best it can be. Once that's accomplished, fine, throw in an Easter Egg to people "in the know", but don't try to make it the main story and let it distract from the base product.
As far as Epcot goes... that was a poor example. Don't get me started :/