There's other problems with that as well. Who really wants to spend the whole game micromanaging in the City Screen? An abstracting the whole ability to change the main map? I'd rather change the main map, on the map, with units, than be clicking around endlessly in city screens without being able to see the whole as I do so.
Other problems, your "pool"'s job, is it indicated on the main map? If not, I'm going to have to constantly be looking in the city screen and the enemy won't be able to see my massive public works project for some reason. If it is indicated on the main screen, then isn't it really just the same thing except I have leave the main map, go into the city screen and fiddle around with this "pool", and then come back out again?
And how am I going to build roads, colonies, forts and airbases outside my borders? That's not a practical concern?

Slaves are about the least of problems here!
When I have "ppols" that aren't doing anything, will there be some kind of indication on the main map or will I have to tour all my City Screens every round, looking for idle "pools"? And if I've got 15 idle "pools" to give jobs to every round, whats the difference between that and 15 idle workers, except that I have to switch to City Screen in addition to assigning orders?
You see, "pools" don't really affect the key problem whatsoever. You'll actually be doing more, not less, micromanagement. The key problem is the necessity of developing all those tiles, which isn't reduced by "pools" you're just making it so that instead of assigning movement orders to workers on the main map, you have to go to the city and go into the city screen and click on the tile. The time it takes to do the movement orders is probably alot shorter, especially considering your workers will come up automatically in queue but your "pools" won't and you'll have to go over the whole map looking for finished jobs and idle pools, every round. I guess you could get rid of that by creating a "pool queue"

but I really don't want my city screens or domestic advisor or whatever popping up more than they already do.