The Arbor Day Foundation and many other reliable resources clearly spell out that tree topping in neither good for the trees, nor effective for the purposes that people are trying to achieve.
I feel so sad to look at topped trees. Some people in our neighborhood recently decided to cut off all of the leaves on their Magnolia tree (photo above). Why? Seriously, why did they do that?!
Some people top trees for fear they are getting too large. In fact, the topping process tend to create a surge of bushy growth from several growing points. Down the road, the topped tree may be even larger than if it had not been topped in the first place. Proper pruning can remove excessive growth without the problems topping creates.
My Top 8 reasons to avoid tree topping:
8. Topping starves the tree
7. Topping a tree will NOT reduce storm damage, instead it likely increases storm damage
6. Topped trees can decrease your property value
5. Topping Stresses Trees (increased susceptibility to insects and disease)
4. Topping Causes Decay
3. Topping Creates Hazards (shoots that form at new growing points are not anchored securely)
2. Topping Is Expensive
1. Topping Makes Trees Ugly
And the "Ugly" isn't over when (if) new branches grow. It will continue to look unnatural...forever.
I think Jim McCausland said it best in a blog post for Sunset Magazine:
Tree topping is usually evil, always expensive, rarely effective, and dependably ugly.
Online Tree Topping Resources