Low-Impact Housing?

One of my co-workers here at Leave No Trace sent me an article about some pretty unconventional treehouses designed by an architectural firm in Sweden. Instead of being made from natural materials, these houses are constructed from large panels of mirrored glass and hang suspended around tree trunks. 

Take a look at the article and the structures at this link: http://www.treehugger.com/files/2009/02/swedish-mirrored-treehouse.php 

A slide show of some other unusual tree houses can be found here.

While I found these houses interesting, I am concerned about the environmental impact that these structures have on the trees, land and native animals. What do you think? Do houses like these create too much of an environmental impact by altering wild places? Or are they a step in the right direction because they blend with their natural surroundings and minimize impact on the ground?