It was mostly logistics that had complications before. If farmers/cooks were assigned due to a rule of thumb you were pretty safe, but that doesn't account for various ways you can build colony. Do agree though, for a while, (after building lab, for example) the thing I was doing was making larger constructions with more iron modules and then superfarming for Quality Food. Making stuff like Iron Ovens occurs pretty early on, and isn't really a major change as... If you've noticed your cooks, once the overseer hits Jolly Good, the cooking time is very short, and the difference between stone and iron ovens becomes (I think) fractions of a second. The main impetus to upgrade has for me been mostly due to the fact that you can generally mine iron infinitely (and it's good for production values and even trade) while in most cases you are seeking out further and further away stone deposits. On the whole, it's a bit odd to think that one of the most late-game challenges (before) was switching from 100% Basic Food to supplying sufficient Quality Food (Farmers' Stew mostly) for your overseers.