I guess I'm more of a visionary than a leader - to put a positive spin on it. Clearly, transporting food in large quantities to people far away is not likely to be sustainable. It is how many live today. So, I assume you are talking about the near future when such ecocities could be realized, and possibly a transition to an even more sustainable future than ecocities further down the line. I could be convinced that it is necessary as a transition.
Assumptions cause wars.
By all estimates I've seen the population is not expected to peak at less than about 9 billion. Cities and their problems need to be dealt with. Rural areas, too, for that matter. I'm sure we agree that anything is likely to happen slowly, perhaps too slowly. Everyone picking up and moving to the country is just not going to happen.