I don't see the aqaeduct so radically important, especially not for an ICS strategy. Due to happiness restrictions you want to have your cities capped in size. You want to have 0 excess food and your population working on either hammer or commerce generating tiles for most of the time. I think an aqueduct is more important for some few core cities, especially your capital. However, an aqaeduct can be interesting later in the game for your "non-core-cities", when happiness is not that limiting anymore (enough luxuries, theocracy, etc). My concern is, that puppets will build it on their own and make cities grow which you don't want to gain in size. So puppets could eat up your happiness supply more than they do it now, especially when located in food-rich areas. Maybe annexing is sometimes a better idea than puppeting now?