I am always amazed to learn how much one can do with with todays processing software. You should never delete "too dark" underexposed picture. It is incredible how much detail & color can be salvaged with the help of Lightroon, GIMP and Photoshop (these are the ones I use). Nobody can say what more can be done with software in a few years from now!
Furthermore you can alter and change the mood and look of an image considerably with the help of textures!
Here is an eye-opening before & after:
I used some of my textures from my build-your-own-texture and a texture from the wonderful
DistressedJewell that you can find here: Free Textures.
Next I will post something on sculpting light with textures!!