Instead of having a food bonus, leading to extra population, which in turns leads to extra everything including unhappiness, we can just have the AI get a bonus on everything except population. Since population amounts is just means to an end, and has complex effects across the board in the game, it'll be far more controlled to just boost the end results (production,gold,science,culture) as opposed to population. You don't get unhappiness problems, and you don't get compound AI bonuses from boosting first population and then everything that population produces.
That said, the human is clearly better at making his cities grow that the AI. So a small boost to AI population growth, one that keeps the AI roughly on par with the human managing his city more carefully, would still be in order, in my opinion. After all, the city and worker AIs can make stupid choices that stagnate the city for a very long time, since the city only gets out of stagnation after it has grown and can pick a new tile to work on.