All closely-mown grass looks unnatural to me. Admittedly, I've only seen Sand Hills from pictures, but those green fairways amongst all the naturally-occurring long grasses, and even the blowout bunkers don't look natural to me at all.
And it doesn't bother me one bit.
Man's interaction with nature, the way it works, the way it looks, is endlessly fascinating, and sometimes stirringly beautiful. I remember the first time I saw the Banff Springs Hotel, perched above its mountain valley, how gorgeously it fit into the spectacle, how it was able to enhance an already-beautiful landscape.
And I feel much the same way about many golf courses. There are courses like Sand hills, that seem to follow the lay of the land, trying to fit in (think Frank Lloyd Wright's Fallingwater), while others (say, every desert golf course ever designed) play off the contrast with nature. Either way, it seems to me that beauty is to be had. Many links courses have rounded, sharp-edged bunkers (like the pictures of Hoylake from a recent thread) that I love, but these are probably less "natural" looking than the heathland bunkers overgrown with vegetation like some of those pictured on the Woodhall Spa thread (thanks, Mr. Schulte). Yet on that same course the hand of man is so very obvious around the greens...........
And I still fail to see a problem with that. If "Natural" is really what you're after as a golfer, head to some empty property, tee it up, and go for it. All golf courses that get regular play blow off nature to some degree, don't they?