If to dream about simple color grading tool, which can be powerfull, but simple to use, here is my prevision of what it could look like
1) engine of this effect is based not on changing original, but on creating coorection layers, and therefore Opacity can be applied and even animated
2) every button is a toggle button and therefore we can create any mix of them, for example on this screenshot we increase
1) only saturation
+ 2) only in yellows (that is red + green)
+ 3) only in shadows (that is what curve does)
+ 4) with screen layers blend effect (corrected 1) + 2) + 3) image blends over itself original)
+ 5) with 75% opacity
+ 6) and rememebered on 1 layer (slot) and 6 layers (slots) are still vacant
and if we want all this stuff can be animated (with Keyframes button)
and masked (with Add mask button)
That's what color grading tool of dream looks like for me. 
))
if you want to see how documentary movie look is
read this topic on this forum
http://nch.invisionz...preset-filters/