(SNP voters crying in the distance)
I'm being half serious though, imagine the benefits: For one, it's easier on RAM (I read somewhere that number of cities and number of civs are the two main memory sinks), secondly it requires less micromanagement, and thirdly it allows good tiles which aren't near any real life important cities to be worked without having to found an ahistorically large city nearby, which is the specific issue we are having with Great Britain. Just split it between London, Edinburgh/York/Manchester/whatever and Dublin and you're good.
This would also address the situation in Siberia where there's Deer and Fur outside the working range of any possible city without having to enable settling on non coastal tundra.
Maybe we could enable cities within working range of other cities to be turned into village or town improvements depending on population size, with all surplus population, buildings and settled specialists being relocated to a city being able to work it in the form of food, hammers and, well, settled specialists respectively, maybe gain a Settler and/or worker for free depending on culture level. Cities which contain wonders or are holy shouldn't be able to be downgraded like that though. This would allow you to spam lots of closely packed cities early game while they are small so you still have enough tiles for all to work and disband them later on when your population gets too large and you acquire some colonies. You can have your cake and eat it too that way: If we take England for example, in the Medieval age you would control London, Plymouth, York, Edinburgh, Inverness, Dublin and Belfast (don't know the exact locations of some of those cities so this specific combination might not even be possible, but it's just an example) and sometime between the Renaissance and the Industrial era you disband one after the other while at the same time building up a Colonial Empire, until you are finally left with only three cities in Great Britain and Ireland working lots of juicy towns.
Lastly this would allow players to do away with badly placed cities without razing them, and for someone like me who would invade his best friend in multiplayer against all rhyme, reason or hope for survival if they dare to settle a city in a suboptimal position that is not to be underestimated.