Great point, you might dream of long range connections sending solar energy from the day into the night around the world.

But, what exactly do you mean by fragility? In what way are they fragile?

That they carry massive amounts of power so they'll help you to destruct themselves once the barrier is penetrated, are actually quite complex and can be sabotaged easily.

This is a nice text on the underwater version:

https://europacable.eu/wp-content/uploads/2021/01/Introducti...