I will try to understand your point of view if you try to understand mine:
I want the grid to be as large as possible so that I don't reach the edge and don't have to feel constrained by it. (In particular, I don't want to run out of vertical space and be forced to expand horizontally when I don't need more space along that axis.) By necessity, this means there would be many grid squares that will never be filled because as we get closer to filling them, more grid squares will be created. I believe that even a premium player should never be able to fill the grid.
This conflicts the the opposite desire of wanting to fill the grid -- of not expanding the grid until the number of expansions exceeds the number of grid spaces. Why would someone want that? A sense of completion, maybe? I really don't understand.
Thanks for explaining further, I think I do understand better what you're saying. And we're indeed talking about different things: what you're saying is you'd love to have the freedom to expand your city indefinitely in whatever direction, meaning that they keep adding more grid squares indefinitely. I think most would be delighted with that in the abstract, I certainly would. The problem, according to the developers, is one of graphic rendering, like what Ashrem said. I heard the lead developer say the grid we have now is basically the max they plan to go, because beyond that the graphics become unmanageable on most machines. I'm certainly not qualified to evaluate that claim, but that's what they say.
So I don't think anyone is saying they are dying to have every grid plot on the map as such. What we're saying is,
given that the size of the grid is fixed, we would prefer to be able to use the available plots rather than not be able to expand further. Yes, that means that everyone tends eventually toward the same shape city, which is the shape of the grid, assuming they keep growing - that is inevitable. But of course no one is
obliged to keep expanding either, anyone is free to keep their doughnut city and work with it as it is! (Though I don't think even anyone in Legion of Doughnuts has a literally doughnut-shaped city - will research further.)
I would add though that this is not at this point purely a problem of premium players; I and others who have bought few to no expansions have reached the hard cap the game has set (at 467 provinces).