Tim,
Obviously, if your fairway area has a twenty foot uphill slope, that won't be changed, but a two foot bump might be. In my reply, I was thinking of little land forms, and also of a current heavy clearing project in the northwoods of Minnesota, with heavy clay and ledgerock and boulders below.
That type of soil and subsoil, combined with the time of year it is cleared, produces lots of ruts from heavy machinery. Also, the owner has contracted with a logger to take the pulpwood and they usually leave a mess. On the other hand, the owner gets about $500 acre for the wood. Oddly, enough, he still pays the golf contractor about $2000 for cleaning up the stumps, etc., but it still saves him some money. It is easier and cleaner to just push the trees out in one operation without logging them, but not as environmentally sensitive as reusing the wood for other puproses. So, the owner elected to use the natural materials on site, but it costs the preservation of small natural features.
Frankly, most professional architects, with Tom Doak perhaps being the exception, or at least being more "PC," route and design holes considering the broad expanse of topography of a given hole. For example, trying to get a dogleg left on left sloping topography to avoid a reverse dogleg slope that might not contain tee shots, locating the hole so a fairway bunker can be positioned easily/naturally in a gentle upslope, etc.
Finding a gentle knob that really falls into the right place is actually pretty rare, at least on sites I usually work on. A Pacific Dunes would be different. My new Quarry Course in Minnesota had some special features that we made good use of but I can't call them natural, since they were mining remnants. In fact there was one feature - a series of mine excavations about 20 foot deep that provide a visual hazard and forced carry of the sixth tee - that I insisted not be touched, and the contractor complied. After the hole was built, I did decided to go in and take the top 2' off the ridges to get better vision down the fairways. Unitl now, I would be the only one who knew that happened. That 2' is not natural now, in theory, but it is a far better golf hole.
I recall remodeling a prominent local club a few years back, basically installing a much needed drainage system. Of course, the fairway grades were increased, and there had to be a few high spots as part of that. One member called my house at 11PM one night and demanded I come out to see a little ridge I added in the fairway. "That's exactly where my tee shot lands, and it will deflect my shot into the rough." I offered to watch him hit a dozen 255 yard tee shots right to that spot, but he declined the offer.
The point is, that many golfers, inlcuding amateur and hobby architects would look at a 2 foot knob, and consider it very important to save. Most architects would look at broader considerations in the topography, rather than look at one little knob. After all, that club member thinks he consistently hits a 20 square foot area 250 yards away, but he doesn't. How can such a small area be expected to really influence play consistently enough to build around it? It can't, unless it happens to fall right at a green entrance or side. Then it can be saved. Anywhere in the fairway (a bigger, longer target with people hitting to a general area) is far less likely to influence play as well as a man made feature placed where it is really needed.
But in reality, after clearing, there are also some shaping operations, general construction traffic, irrigation and drainage installation, fertilizing, and then grassing. That two foot knob is going to get far more action during construction than it will ever see from falling golf balls, and it will almost never be preserved exactly as it was. In fact, if I was using it as a feature, I would probably double it's height to account for the beating it was going to take before grassing, as well as nature's tendency to erode things to a flatter state.
All in all, that little knob could only survive modern construction as a mere representation of it's former self. Of course, although machinery is bigger, I don't think that things have changed all that much, as frankly, Golden Age architects spent more time, IMHO, and based on study shaping approaches to greens than we do, because the approach was a more important component when run ups were common.
I say this thinking mostly of MacKenzie courses, like Royal Sydney and Melbourne, and the Cypress Point. If you look in Geoff's club history book, you will see that the Doctor fashioned many approaches artificially. In fact, many have a gentle concave slope to the middle, which helps balls driect on the green, and makes the green present better. Frankly, this strikes me as similar conceptually to - gasp - a Fazio concept!
Let the discussoion continue!