Read back over the thread, and you'll see how hard it is for even a very knowledgeable group to get over the idea that the hole handicaps are the order of difficulty of the holes, rather than the likelihood that a bogey golfer will need a stroke to equalize to a scratch golfer.
Here are Jordan Speith's birdie (or better) percentages on Tour this year:
par 3's: 17.96%
par 4's: 20.8%
par 5's: 51.6%
So think of it this way; even if a par 5 seems like a relatively easy chance for a par to the bogey golfer, at least as par 5's go, he'll need a stroke from a good player most of the time because that better player is going to make birdie or better an inordinate amount of the time.
Meanwhile, Speith is only a third as likely to birdie a par 3, so even if it is a very tough par three, the lesser golfer is less in need of a stroke to equalize.
If handicapping of holes is done correctly by a given club, it's off of a large database of actual scores by scratch and bogey golfers. "Difficulty" is a subjective term; for one guy, it's about length, for another it's forced carries, for another it's bunkers, and so on. Of course there is going to be a correlation between the index and generally accepted levels of difficulty, but there are often exceptions than mystify golfers who misunderstand what the ratings mean.
One more thought: Indexes for holes are reckoned from the back tees, and there are MANY cases where the hole changes dramatically as you move up OR change the angle of the tee shot. At my home course, the #1 handicap hole (#16) is 427 yds from the back, with a 200+ carry over marsh to get to the fairway. From the next set of tees, the hole is only 361 and from the third set of tees 315, and ALL of the yardage reduction is forced carry! Players who have never played the back tees are often mystified by why this is the #1 handicap hole; I always urge them to take a look from the gold tees and see what they think from there.