Having worked in wetland restoration I can say with confidence that section 404 of the CWA was always only a fig leaf that slowed but did not substantially reduce destruction of wetlands - typically what would happen is a project would get approved and then follow up was shifted to the localities who would have an incentive to ignore projects that failed. There was more enforcement if the area was an important to endangered species or migratory birds and the EPA would occasionally pursue enforcement on unauthorized alterations, but the statistics demonstrate that wetland area in the States has been in continuous decline going back to the colonial period.

The really funny-ish irony in all this is that the reasons for protecting wetlands in the first place were mainly economic - wetlands serve as important buffers for floods and capture storm runoff. You typically don't want to build in low-lying frequently flooded areas because that'll cost you in the long run. All this decision does is ensure that the consequences of climate change will be even harsher in areas that experience increased rainfall. But the dudes must rock.