The par-4 16th:
Regarding the issue of topographical interest at Hazeltine, it is true that most of the slopes are gentle (though #9 and #18, while unfortunately similar, parallel holes, are steeper than they appear on TV), with the exception of the point where the plateau drops dramatically down to Hazeltine Lake. That drop was actually used better in RTJ's original design, though the rest of the design, with its 90 degree doglegs, was a valiant but ultimately doomed effort to combat the new wave of long hitters in pro golf. RTJ's original #10 -- a sharp dogleg left with a steep drop down to the green -- remains more or less untouched, and most agree it is one of the best holes on the course, if not one of the best he ever designed. He also used that slope to create two NLE holes: the downhill par-3 16th and the short, uphill dogleg right par-4 17th.
The 16th (with a tee located to the left of where the above photo was taken, and its green to a location left of the current 16th green) was controversial because of a huge cottonwood left of the green that created what many called a dogleg left par-3. That hole would have survived, however, had the pros and P.J. Boatwright of the USGA not developed an almost pathological hatred for the 17th. It required a mid-to-long iron up the hill for placement, and then a short iron or wedge to the green (which still exists on the current par-3.) In the 1970 Open, Tony Jacklin hit through the fairway and had to punch out of the trees from his knees and managed to save par. Was it a great hole? No, but it was not the abomination the lynch mob claimed it was. I thought it was a fun hole, and still prefer it to the relatively dull par-3 17th. But Boatwright told Hazeltine in no uncertain terms that the Open would never return to Hazeltine unless the hole was changed. After bringing back RTJ to (reluctantly) tweak the course but still not winning USGA favor, the club finally bit the bullet and changed 16 to its current par-4 iteration and converted the hated 17th to a par-3.
With those two changes, Hazeltine essentially eliminated the use of that steep drop on two of the three holes that originally used it. I think the current 16 is a terrific hole, but it is dead flat, running along the lake; if the tee were up on the hill near the 15th green (somewhere near where the above photo was taken), it would add an element of drama that is now missing. I suppose there isn't enough room to do that, but that picture makes me wish there were. And, of course, the shot back up the hill on the original 17 is long gone. Hazeltine is a better course than it used to be, but there are some missed opportunities, too.