Any instance of overreaching is promptly acted on by Congress.
Sure. And Santa Claus is real. Must be nice out there in fantasyland.
The government does so much these days that no one can keep track of more than a tiny bit of it, and that "no one" certainly includes Congress. The government issues some 80,000 pages of new regulations every year. And somebody thinks Congress reads all that stuff, or even cares much?
I doubt that the FAA is going to adopt a 400-foot rule. Even if they do, I doubt that they'll enforce it. Still, it's something they might do, and their Deputy Director has talked about doing it. The sky isn't falling, and it probably won't, but it's too early to be sure that everything is just peachy.