but I think the biggest factor is if inno just stopped giving production quests because nobody likes them and they are counter productive to good city building (what should be the purpose of the game).
City building should be a focal point of the game. To make city building interesting you need diverse and competing objectives such that you're making tradeoffs. Tradeoffs like "how many production buildings do I want for the quests I know I'm going to have to do?"
You could maybe get away with only 6 but have it be highly annoying. Or 12 and have it be somewhat comfortable. Maybe you have a flex area that can sometimes be blacksmiths to backup your 6 sleigh builders you use for "productions your age" when instead it's "24 8 hour productions". Which then raises the question, what does that flex area do when it doesn't need to be blacksmiths for you? These are all interesting questions brought about by having production quests be a fixture of events.
There needs to be more to city design than "how many OP event buildings can I squeeze in to max out combat stats or FP production?" Freeing that area you use for production quests does not make city building more interesting - it just means you stuff another couple OP event buildings in their place.
Not saying I don't complain about production quests, but they do serve a purpose.