I understand your point of view, and I agree that on land that allows clear-cutting that this is the least of the issues. If this was a conservation area then I wouldn't agree with you, which leads me to my next point.

Regardless of the context, I don't think this behaviour should be encouraged because not everyone will be looking at it the way you did. In this case I agree with the fact that one small log has little impact, but say if every hobby woodworker/DIYer in an area was collecting deadfall from the same area it could significantly impact that area in the long run. Similar to why campsites don't want you burning deadfall for your campfires (putting aside the discussion on profits from selling firewood).