Because nature is nature and not the sum of pixelized contours. This oversharpening turns everything to some kind of coarse look of those early computer games. The sense of wood is missing - it's rather metallic this way. As if somebody would have covered the tree with aluminium foil or something similar. This is why it can't be taken as nature photography.
why miserable, nick? even if it would be intended as a 'nature/al' photograph/documentary the sharpening would not make it miserable... the digital sepia toning maybe.
A good find, really, and so also a good attention about what is around. The oversharpening... well, another one of "your own" style, let's put it this way. If it was intented as an abstraction then nice and fine. If it was intented as nature photography, unfortunately miserable.