bonafide11
Worker
'Some reason' is because how they are scripted; it's deliberately done this way by the map designers, and most people don't like it.
Your post was the final push I needed; I just wrote a small tutorial for how you can get your City States back to normal in Pangaea- and ContinentsPlus: http://forums.civfanatics.com/showthread.php?p=11252161#post11252161.
I hope this helps people!
I just bought the Explorer's Pack yesterday because of this thread, and the first map I tried was Pangaea Plus, but I couldn't stand how everyone was packed on the same mainland with no city-states. I might have to try your edit of it.
Has anyone else tried it? Does it work better? Is it too crammed?