Most of the rural areas that the universl coverage concept is intended to serve don't have water lines running from a central location and may not even be connected to a large grid. Satellite internet serves remote homes and scientific outposts in a way that cannot be met with physical lines and depending on terrain it may not be possible through towers.

When you are living in mountain vallleys or working in the middle of a desert having the same access to the internet through a non-physical connection is crucial.

That said, the current implementation has some serious downsides and we should learn from that in a future iteration that requires fewer physical objects that are far less reflective than the current models.