I love the idea of small mounds or undulations around greens redirecting approach shots (and chips and pitches), so long as they blend with the green complex.
In particular, small mounds seem to present a mental challenge the the better player who is thoroughly considering all options, while hardly being noticable to the less accomplished player who is merely trying to hit the shot somewhere on or around the green.
Small mounds also seem to be a very subtle way of adding a little more challenge to what may first appear to be the safe route onto a green.
Rustic Canyon effectively uses mounds in and around many of the greens. The mounds not only dictate the proper angle of approach, they also chipping and pitching much more interesting.
As for the claims of unfairness, I don't buy it, unless the mound is moving from day to day or shot to shot, like a mouse under a sheet.