twenty_one,
(just a bit of philosophy for Monday morning 
)
Maybe we have to make a difference between photography that is documenting a point in time and photography that expresses a vision that is different or more than what is "out there".
Documentary photography (photojournalism) - should not be altered at all. Whereas "visionary" photography can be altered freely since it does not pretend to document.
The boundaries are not clear cut, and so it's up to every photographer to see and find out where he/she fits in and what kind of photography he/she does.
In my opinion, Ansel Adams was a typical "visionary" photographer whereas Cartier-Bresson did documentary photos. The question for the photographer is: Where am I standing?