Firstly, it's impossible for a picture to have no post processing! There always has to be some process to either get a negative onto photo paper or a viewable picture onto your screen. The only difference is who is in control of the process, whether it is you, the print company or the person that designed the algorithms in your digital camera to create the jpeg images from the sensor data!
OK, so that was probably a little misleading but the point is, post processing is not new, it's been happening for years, most times without you even knowing it!
The problem with in camera processing is sometimes it just doesn't get it right and doesn't reproduce what your eyes actually saw. This is due to camera sensor technology being inferior to the human eye and the algorithms needing to cater for a diverse range of scenes.
As you can probably tell, I do post process my pictures, as I like to be in control of how my photos look. I use Adobe Lightroom as it's easy to use and provides a cataloguing function also. (Which reminds me, I really should add more tags to my pictures!)
Sometimes I just do very basic adjustments to get the picture to look like what I remember. Then there are other times when I let my creative side loose and go all out!!! It really does depend on the picture itself, it's not uncommon for me to go through numerous iterations on the same picture while I try out different directions, but that optimisation can make a big difference to the final image!
Saying all that, software can only help you so much, it is always best to get it as right as possible in camera as that will result in better pictures overall. It will also save a lot of time on the computer, which you can spend taking pictures instead!!