Although it is fun to putt on extremely undulating surfaces once in a while, regularly four putting roller coaster greens soon gets tedious for most mortals. By designing in such a way that playing to certain parts of the green is far riskier, it is possible to make greens challenging for better players whilst still playable for everyone else.
At IVGD, we usually take a reasonably sober approach to our greens' topography. Many would probably describe our greens as mildly undulating (though some at De Swinkelsche, one of our recent courses, may well disagree). Instead, we provide many closely mown runoff areas around the greens in order to make things interesting.
The majority of players desire to hole out in two putts on each green if they are putting well. They desire to experience some little difficulty in doing so, because otherwise they would derive no pleasure from success. Therefore a perfectly flat green would not satisfy them. On the other hand, when they have avoided the bunkers of the fairway, when they have eluded the traps which guard the entrance, and have played their ball on to the putting green, they do not like to find it is lying in a severe form of hazard
Harry S. Colt “Some Essays on Golf-course Architecture” 1920