I think that you hit the nail on the head; it wasn't going to meet expectations.
Even during filming there were a multitude of stories about it going wildly over budget, about the floating town set being wrecked in a hurricane, having to chase the boat with Costner tied to the mast because it got away from them in high winds...
I liked it fine, but to do so I had to divorce myself from all the hype prior to its opening. And from the negative press, that declared it to be a terrible, over budget fiasco before anyone had even had a screening of it.