You want to improve them in order to have enough financial capacity for park maintenance. You also move the people together in order to keep the population. The main thought behind it was that you could not afford a park if your town is poor. But if you have less poor people and more rich people you could have less houses and more parks. And as usual you first build them up then milk the money out of them and then push them out of their homes to enforce the law of eminent domain. I did have a lot more plans but not the adequate amount of time. A week kinda flies by even if i barely slept.