Being a programmer and trying to figure out why it's like that, I wanted to draw your attention to the fact the bar also reflects some information about the player status.
For instance, I have lots of old friends having left the game who are still in my list. They're now obviously used as farms. As such, some of them are displaying the red "ennemy" background on the top ight corner icon displaying their city level.
They're also displaying the level itself and their coalition logo : all 3 information (including the color) can be subject to changes, and the color one is probably the one that would change the faster, depending on what you last did to the city.
Plus new friends can be added on the go (someone having just accepted your friendship request, for instance).
All this means the bar has to be refreshed to show these changes (for instance if you send reinforcements, liberate, etc., which can be done from the city you're visiting).
Rather than doing so in real time (though maybe it does at given intervals), they apparently chosed to do so only when refreshing the bar, wich apparently occurs only when you display your city or any other you're visiting.
I agree they obviously chosed the lazy way, i.e. refresh the bar by displaying it back from the start, but it's most probably the reason for this behavior.
I mean they didn't do it that way just to bother you, but because they it was simpler like that and they didn't get back to enhancing it since then...
To change this, they would have to store the leftmost city displayed on the bar before refreshing, so they would display it from this point after it's been updated.
However, don't forget the bar allows continuous scrolling, meaning you can see only half of a city portrait if you scroll the bar that way... So which one would they pick ? The next one to its right ? The one that's cut in half ? I think they thought something like "oh, nevermind, we'll address this later" and forgot about it. ^^
OK, so now griefs have grown public about this, maybe they'll have to work on it.
Anyway, I can certify you have been heard. I can't promise when they'll do something about it in a near future, but now you've got more chances they'll do. :)