Before I say too much to get me in hot water, let me state up front that an approach to get perfect or optimum JPGs out-of-camera (OOC) is reasonable and acceptable. If that's your approach, I'm not putting you down. You may not have the time or inclination I have to push for achievement of the "greatest image potential," and for your purposes, what your camera gives you is good enough. However, I'd like to use the following example to show why PP is essential to me -- and I won't be talking about "saving an image" or correcting WB, things that often require NEF (raw) shooting for best results.
By way of illustration, here's what my Nikon D80, with custom Picture settings, gave me. Yes, I shot this RAW, but since I did a straight ViewNX conversion, this is essentially what an OOC JPG would look like.
Since I was there when the camera took this shot, I'll testify it is a pretty faithful representation of the scene the camera saw. No exposure hickups, no incorrect WB -- that's a pretty "nailed" result. It's also rather blah, most of us would agree. And I could have avoided this through more saturation or "vivid" settings in my camera, but my basic issue with this is I can't fathom settings that would give me the effect (and now we are talking about artistic considerations, or what Ansel Adams would call "pre-visualization") I want for a given scene without adding post processing to the mix.
This is blatantly obvious when it comes to B&W conversions, such as this one:
And also for color enhancements:
Here's the bottom line for me: I wouldn't waste the time or money to print the OOC version of this photo, and even if I had "nailed" the camera settings, this would be the case because there are no camera settings (or hardware filters I can use) that would give me the color contrasts in the color version or the texture, shadow, light detail in the B&W version. Post processing is a must to achieve the last two images, which I would be more than glad to consider suitable for framing.
For those of you still on the fence about this post processing thing, keep trying to get the best you can out of your camera, but consider also how you can exploit that optimum result to maximize the photograph's potential. To see more details of how I achieved the last two images, feel free to visit my blog at http://esfotoclix.com/blog1/?p=931