I'm only now and then on the Galciv III Steam Forum, but have the impression the devs are more present there than here.
I just stumbled about a post of Brad that I think we should discuss here also because I think I'm not the only one that doesn't monitor the Steam forums so closely 
Here is the post:
"I've been thinking of the city feature a lot.
Fundamentally, I kind of wish planets had more tiles on them. Because right now, if a typical planet is a class 10, that means 10 tiles and a city uses a tile and therefore needs to provide some benefits.
I've had some..ideas on that that I would love to discuss with you guys.
One of the changes in Crusade is the idea of having hubs early. I'd like to see a lot more of those too btw.
The factories and such are not supposed to be your primary way of specializing a planet but rather a way to take advantage of specialized hubs.
So what if we made cities be a more general hub. That is, they provided some population (like say 9) but also provided +N resources based on whatever was adjacent to it. So you put 4 factories next to it and it would provide a bonus 4 manufacturing points. This would make cities more valuable than they are now without it being so hard to handle approval."
Personally I find that a great idea.
And I agree that planets have not enough tiles on them, especially to take advantage of adjacencies. That's quite hard if a class 8 planet has tile clusters of not more than two adjacent to each other ...