Hehe, I can imagine Seoul is very convenient. It sounds a bit like European cities with all the transportation and stores , but with things open 24/7 and not 8 to 8 as here in Germany.
Really, buying organic fruit and veggies and sugar and milk and all that is a speciality in the US? Her eeven the cheap discounter stores have at least some "organic".
But is it worth it to cook yourself when in the city? If takeout or restaurants are not so expensive, it may be more fun to just go there and use the time saved from cooking to look around the city?

But then again - cooking is fun and you are sure to avoid weird food or spicy stuff. And you can relax after a day touring around. So yeah - having a room with a kitchen seems nice
Do you sometimes need those air filter masks I have seen common in parts of Asia?