The problem is that in the past most (not all--see below) fires were relatively low intensity and spared the big trees. The ecology of our forests in fact depended on periodic fire. After over 100 years of fire suppression fuels have built up to the point that fires are much higher intensity, the big trees die, and there is severe erosion within the watersheds. So letting a fire burn after decades of suppression is not really a natural phenomenon. There certainly has been in the recent past more of a philosphy of letting some fires burn--the Yellowstone fire a few years ago was an example, and a very controversial one. I don't know what the current Forest Service thinking is (but whatever it is it will be different next year.)
No disagreement. I was over simplifying. As I understand it, a climax forest can take sometimes hundreds of years to be established after a severe burn, as the area goes through various stages. I agree 100% with the rest of your post as well.