Pancakes are always a good idea
Essentials have to be transported in. Cut the support and cities become deserts. They support very little biodiversity on their own.
Humans don't like to live in swamps. There's too much biodiversity.
They are hard to build for. Too little nature and they die. Too much nature and they die.
Their information is also confusing. Humans say they like lions and tigers and bears. Then you show them the plans and find there is a surprisingly strong “Not in my back yard” contingent.