Who wouldn't want to go from the outskirts of town to the centre? Truth is (at least, that's my opinion) cities are huge but with very few people in them.
It's about performance. If you want a game that simulates and tracks every cim in the game then may I suggest you play the new SimCity with it's tiny maps. As it is some players with only 3 gb of RAM have trouble running CIM2. With the size of the maps it'd have massive performance problems if all the cims were simulated and tracked.
The game only needs a sample size (which CIM2 does) so you can gather data on their destinations.
My system has 12 gb of RAM, I run it on ultra with no performance hits at all. CIM1 however did have a performance hit when panning around because of the amount of cims. If everyone had decent computers (ie over >8 gb RAM) then games could be better. I suggest you learn to except that simulations games are like this because it's not going to change any time soon.