Later on, the government brought him some beavers from elsewhere, and they flourished.
I believe this is called "Process-Based Restoration".
But it feels like there’s a bit of surprise to the idea that the environment takes on the form it takes on. And if you take away a part of it, it’ll take on a different form. And if you put that part back, it can take on the earlier form. There is no correct or canonical form.
They also provide an invaluable service slowing floods, creating fisheries for humans, and increasing touristic appeal from a location (we are naturally attracted by the aesthetics of watching water). Ponds also create relatively safe sanctuaries where wildlife, cattle and humans can retreat in case of wildfires.
So, yes, there are many cons, but also many pros. Beavers compete with us for low places and shouldn't be allowed everywhere, but to eliminate them from every place is also a mistake.