The plan of Tomorrowland wasn't to make a Utopia and say screw the rest of the world. The plan (explained more clearly in this clip https://www.youtube.com/watch?v=w-USh0Womb4 that it probably was in the movie) was to free the most creative minds from the pettiness of mankind so that it could rise above. Once this utopia was complete it would be presented to mankind fully functioning to say: look, the future is here. Now leave all your crap behind and join us.

Tomorrowland was never meant to be a permanently exclusive thing, just long enough to get established.