Wow this thing really really became heated. Having worked at the resort and done an extensive amount of GC and crowd planning I thought I would toss this in. Both tram stops dump into the Esplanade which in turn feeds the parks. It serves a vital role in keeping the tram unloads clear, allowing more Guests to wait for their entrance to the park.
Pre 9/11 without the security checkpoints the Esplanade would fill up even faster and it was not uncommon to have people waiting for Disneyland while standing at the California letters.
Post 9/11 the Esplanade fills at a slower rate and when the gates are opened it allows the gates to catch up to the inflow and eventually as less come in the Esplanade slows down. On extremely busy days they will close the gates, generally around the 12-1 time frame due to park capacity but I have seen it close as early as 11am. At this point people must make the decision to either wait for Disneyland's gates to reopen, or go to DCA. MANY chose to wait and the Esplanade begins to fill up again.
As has been noted multiple times DCA's main entrance is now going to extend to the current letters. In the past they have had various contests; most noteably a Honda, various premiers, and several sculptures. In ALL cases the Esplanade became more crowded. Having a fountain would increase the leisure traffic, thereby increasing overall foot traffic. Instead of the Esplanade being a place of transition, it would become a meeting point, a rest stop, a relaxing stay. More people would stay there which means less room for those who are simply waiting.
I am not sure if you have tried this experiment but if you stand on Main Street and just stare at a random spot on a building, people will stop, and stare... that's how crowds grow. They REALLY do not want to make a crowd in the Esplanade and that is what a water feature would create.
Knowing that this would displace individuals even 10& of the time... where would these individuals go? They walk off the tram into...?
As far as my personal experience with the park and crowd control, I helped with the design and implementation of a variety of crowd control scenarios. I know crowds and this will cause one.