Not doing anything might indeed be better for the environment alone in isolation, but has to be balanced with other considerations, like the benefits of a power cable carrying clean power from wind farms to replace coal.
It is also entirely possible to plant native, locally appropriate seeds in a reasonably natural fashion. I am obviously not proposing a layer of lawn sod.
I think that's a question for the ecologists.
My guess, though, would be that part of the concern is people visiting the site on an ongoing basis as a tourist location, which won't happen with a buried power line.
Now ask the ecologists if bulldozing and paving over hundreds of square miles of forest to make a city is ecologically sound. You might be shocked to learn that your entire so-called "civilization" is a pox on the planet.
I think I'll take my critiques from people who don't have shit like this in their comment history. Thanks!