There is an excellent article by Ed Brockner on the restoration of Plainfield Country Club in NJ in the August 2007 issues of NJSGA Golf magazine.
Ed addresses the changes made by Gil Hanse by indicating how the course was originally designed, how and why it changed, how and why it was restored to original as applicable. Each of his points were supported by quotes from the original architect, Donald Ross.
Example of the article, "This ongoing process resulted in a course that no longer dictates the line of play but now offers a variety of options that challenges all levels of golfers." "While those selecting the more conservative play (now available after taking down trees) will not have to carry this daunting hazard, they will also face a longer shot with a more difficult angle to the green."
The article has a lot of concise one and two liners to explain the conditioning and playing benefits of fewer trees, angles provided by wider fairways, playing options provided by cutting down greenside rough, the increased hole locations and improved turf conditions of restored (generally larger) greens, and the risk and reward benefits of properly placed bunkers.