The problem is that none of these posterisation algorithms (reducing bit depth of channels and optionally dithering) match the quality of somebody placing the pixels by hand. It always looks more like 'deep fried' images as opposed to pixel art. None of the samples are appealing (except for perhaps that one with palm trees).

I would look at them more as a tool that you could use as part of your toolset rather than a complete replacement.

You can put an image through it and then do manual touch ups, copy and paste other images and so on and start building a composition.

The Blade Runner one is missing the buildings, robocop has no mouth, BJ is missing part of the right side of his head.

Just started watching that talk, lots of extremely impressive artworks, I'd never heard of the colour cycling techniques he talks about before which are very neat.