If one is living with a roommate, chances are they can't afford living on their own. Batch cooking saves money in the long run (and you don't have to be poor to cook in batches).

This rule I disagree with. It's a personal opinion to see it as rude. Having said that, it's all in the communication that can be sorted out. I used to batch cook once per week so if I had a roommate, I'd explain this and compromise on a schedule that works for everyone.