This question has been beaten to death really. However, I would like to write about my opinion here.
I have to first admit that I am an advocate for post-processing. There are many arguments proposed by antagonists of post-processing. They would argue that a photo is only “real” if it has not been post-process, that post-processing is “artificial”. Post-processing is a “lazy” way of achieving a good photo and that a good photographer should use good shooting techniques to obtain a good photo.
Well, it is true that one should not substitute basic good shooting techniques with post-processing. Maybe one can improve a poorly shot photo with post-processing slightly, but it is impossible to make a poorly shot photo into a great photo. However, post-processing can be used to enhance many good photos and make them into great photos.
Post-processing is really nothing new. Even in the days of film, many photographers, especially professional photogrpahers perform post-processing in their darkroom. It is at least half the reason why photos by professional photographers were always better than those by shot by the average Joe and processed in your friendly local neighborhood photo lab. Darkroom “post-processing” was a powerful tool that professional had which the average photographer could not afford in the days of film.
One of the major advancement with digital photography over film is that, the average photographer suddenly have this powerful weapon called “darkroom” available to him or her. The digital darkroom lives on your average PC and is available to anyone who is willing to learn how to use it.
If you give up on this powerful weapon, you are giving up on a major ability to improve your work. Many photographers would not give up the chance to own the latest and the best camera body. They would not hesitate to buy expensive lenses with the best optical qualities. All these are done in the hope that they will get better pictures. After buying expensive cameras and lenses, why do some of these photographers want to give up the chance of being able to get better picture quality by giving up on post-processing?