There is actually a nice library for adding in logging after the fact as you say, PostSharp. It lets you do it via attribute-based programming, among many other very useful things beyond just logging.
I agree that what you say is a little excessive for logging.
Some others bring up some good points, especially the banking scenario and other mission critical apps. It may be necessary for extreme logging, or at least be able to turn it on and off if needed, or have various levels set.
