They don't have a choice. About a third of Jakarta is already below sea level. It's sinking fast and the rains are becoming heavier and unprecedented more often. About a quarter of the city will be underwater in 25 years.
It's a gamble. Design a new planned city with 60% rainforest now and in 75 years it will be a new metropolis but better thought out and with sustainability in mind while other cities fall into the ocean.