Popularity has nothing to do with the decision. Disney believes that Epcot is "too big" for the current price of a ticket. They want to reduce costs, i.e. the number of attractions a guest visits in a day, down to a level similar to the Disney/MGM Studios and Animal Kingdom. Since they can't charge more to get into Epcot, they want to make sure it costs them less. They believe it's better to have one attraction with a 30 minute wait than two attractions with a 15 minute wait time.
It's unlikely they'll do anything until the 'Nemo' attraction at 'The Living Seas' opens. Not only will that be a draw, Disney may decide to force the issue as well. If I had to bet, I say you won't see the dinosaurs the moment the fish shows up.