I also wonder why players always complain about all the event prize buildings.
1. No one says you have to build them all. Choose the ones that best fit your playing style.
2. If you have a Chateau and not finishing all the quest your just hurting yourself in not take advantage of the free stuff.
3. Expansions never need to be a reward, this is a strategy game, build your city to the way you want to play. That is why they give you the ability to have a city in every world so you can play different strategies.
4. Save the buildings for future if you have, I am sure something better will come out that is event better.
5. If you are worried about the supplies and coin cost to build a building for the quest, then you need to rethink how you are playing. Maybe you are rushing up the era's to fast. If you have not looked at what the coming up quest for the Halloween event then you are going to be in trouble.
6. Inno is not forcing anyone to purchase diamonds, IMHO for those that keep saying this have no idea how to play the game and should go read the tutorials and study up on what strategy means.