Lawns replace existing habitat with a monoculture of a non-native plant. The untended yard you labeled as "negative" supports a local habitat and ecology - those native plants support insects, reptiles, birds, squirrels and other wildlife. The lawn is a far more sterile space, an ecologically near-dead zone that only support grubs, ants, and a few undesirable insects but primarily is lost habitat. Lawns are among the drivers of habitat loss that are driving species loss in the US. During a time of global warming where droughts are becoming increasingly more common we've got lawns wasting that water. Lawns are objectively harmful to the environment on many, many fronts.