i think the real problem with ics is neither the global food bonus nor the global communist production bonus. it is the happiness mechanic that's not working here, and this is due to the fact, that even small towns can easily be happy-neutral AND profitable commerce-wise at the same time.
i have mentioned a possible solution to that before: make the first happiness-building, the colloseum, produce happiness in relation to population (+1 happiness per 3 population for example, possibly but not necessarily with an upper cap of, say, +6 happiness). no need to fix a myriad of different mechanics, just one simple fix and horizontal vs. vertical expansion gets to be a real tradeoff, like it should be.