Slightly off topic but…
And poly-painting does indeed have some awesome advantages. It is directly on the model for sure, and doesn’t need UV’s. All good.
Problems with it:
I work in games. We use textures. If I want to use polypainting (and I have) I’m limited in a number of ways as far as the pipeline goes. Firstly I ideally need to be painting on a low poly model as that is what the games model will be. If I subdivide the mesh numerous times it begin to ‘bend’ the final result. E.g. a straight line I’ve drawn can warp as it tries to transfer back down from a high poly to a low poly. The way round this (aurick I think suggested this to me) was not turning on the smooth when subdividing. At which point you’re trying to paint on a faceted edged model.
Compare this to, say, the simple tools in other 3d apps. I load in a texture (or create one) and I paint away. I can paint in flat color or with a material shader turned on. And ultimately it’s given me much closer results which I need for my field (games).
More importantly the texture sheet is useful because people need to be able to quickly adjust things. Addings scars, changing hue tones or whatever. I need to be able to pass this over to another artist and say ‘I did this earlier… can you change a few things like adding makeup, dirtying the character or something similar?’. We reuse a lot of textures like this. I don’t want to have to give them a collection of non UV’d squares that need the source model to do any work on 
Pixel painting is ace - and fun - but for my games workflow we need texture painting otherwise I’m forced to abandon zbrush for that part of the pipeline.
