The par 3s seem a tad repetitive in their shot requirements even though they look totally different from the tee, with the exception of the short 16th. I also think they might be a touch over the edge and into penal design with the length necessary for them.
Chris, I imagine you've played the Hill course far more often than I have, so I'm inclined to defer to your judgment. But my memory of the par 3s is much different. I thought that (a) they all ask for quite different shots, even if the lengths are somewhat similar and (b) they are not penal in the sense that anything other than the worst miss allows for a difficult, but possible (and typically fascinating) recovery shot. What do you think makes them too similar? What do you think makes them penal?
As an example: the fourth for me is a long iron, and on the day I played you had to do two things with the long iron shot to be successful. First, you had to get it over a quite steep bank fronting the green. Second, you absolutely, positively had to keep it below the hole; anything above the hole and not very close in meant a likely four. It was no mean feat to do both of those things at once, since that meant hitting either a soft shot with a long club or playing something low and creative into the bank. While none of the recovery shots seemed easy, none of them seemed impossible, either, unless you ended up both above the hole and on the wrong side of one of the vertical ridges coming in from the back of the green, in which case you needed to take your medicine and put your chip somewhere that would allow you to make four.
That to me is very different from six, which for me was a fairway wood to a receptive green with a bowl in the back (meaning that the primary challenge was to a hit a very long shot very straight, but eliminating the need to hit an unusually soft shot), and from thirteen, where the green is a series of bowls and the real test is controlling the distance on a fairway wood shot (something I hardly ever find myself asked to do). And sixteen, as you say, is just a completely different kettle of fish. It's over 50% shorter than any of the other par 3s and it makes you think a tremendous amount about placement and trajectory even though you only have a wedge or a nine iron in your hands.
I think both thirteen and sixteen are world class, and that the other two are worthy holes as well.