Meh, I guess I've never played a course with more than 2 or 3 so I've never worried about it too much. Diamond X has one posted 15' up on the side of a cliff and I don't think I've ever heard any complaints about that one. I've seen some 8's, 9's, 10's and "I quits" during tournaments, but no actual complaints about the pin placement. To be fair, you can land on the cliff and its a standard putt(with a 15' cliff behind the basket regardless of where on the cliff you land).
To me fun courses are about variety so as long as the pin placements aren't repetitive and can add some unique challenge or risk/reward aspect, I'm fine with them. If every putt on a course is from a nice flat green with a 3.5' high basket that just doesn't sound like the most fun to me.