Mature beeches can be susceptible to many fungal and bacterial infections. This is a natural process and in the right place, the tree could grow old gracefully, shedding bits and pieces as we all do in time. Depending on the type of infection, beech timber can rot very quickly and cause a large tree to become unstable and therefore unsafe.
The Arborists report will tell you why the course of action has been taken.
It may not be best practice to replant with the same species because of the aggressive nature of some infections i.e.
Honey Fungus.
It's always sad to see a beautiful tree removed before it apparently has reached the end of its life.
The presence of bats in a tree may not stop its removal if public safety is the overriding concern.
In south Cumbria, a number of beeches were removed on similar grounds some years ago in the Rusland Valley by the National Park Authority in a well knownh beauty spot. When they were felled and lying on the ground, the rot holes, cavities and problems were plain to see. There was a great uproar at the time, I think due to way in which the NPA handled the incident, but that's another story.