I was thinking; because a easement is recorded on the host property (generally), what happens to the easement when it is no longer needed? This would apply to both utility and access easements. If a power company bought rights to 20 ft easement, and they aren't paying property tax on it; I wouldn't think they would want to just turn it over. It would be 'nice' if they had a clause where they were automatically vacated if unused for a period of time.
If your rear neighbor had an access easement across your property, and he buys another parcel that Does have direct access to the roadway; it would be good if that automatically triggered that easement across you going away. I also see the argument, if you paid for that easement right, you wouldn't want it going away.