Trees, shrubs, and other geographical features change and will keep on changing. As for the effect on the value of one's property, it sounds to me like you are using it for an investment. Let me tell you, the value of any investment can go up or down. Again, that's life. If someone is willing to pay an inflated price for a home with a view, I am sure they are aware that what is there today may not be there some years down the road.
Nothing stays the same forever.
I hope the perpetrators of the tree girdling are caught and convicted. Then, if it turns out that it really was done for the view, they should be accessed a fine equal in amount to the artificial rise in value of their property. Please show me where on the Deed of Trust that it says anything about owning the views from the property. My neighbors have some tall trees that block portions of my view, but I would never think of trespassing on their property and destroying their trees. As a homeowner, I've pruned trees on my property at the request of my neighbors, but I'm not going to cut down or remove every tree or shrub on my land to enhance my neighbor's view.