Phil,
I think a blanket statement such as yours is way off, not because there aren't a lot of dull three shot par-5's, there are a huge number of them, rather because the statement lumps holes such as the 4th & 13th holes on Bethpage Black into that mix.
During the 2002 Open, with both holes reachable in two, there was not a single eagle made on them with 2 shots & a putt.
The 4th hole, which will still be played at about 535-540 for the 2009 Open can bereached with a drive that catches the hill in the fairway that will sling the ball down the hill just short of the cross bunker. Tiger placed his drive there on Sunday when he was struggling & his lead in doubt. His play from there? the proper one, to the fairway portion right of the green from where he made... par.
What makes this hole a three-shotter is the fairway elevation changes & the green that slopes away from the player.
The 13th can be stretched out to 590 yards & yet can be reached in 2. On Sunday in the 2009 open, Phil was just short of it & Tiger reached it in 2. Yet for even good players, at that distance it becomes a hole of choices as the cross bunker about 40 yards short of the green is definitely in play. If a lay-up is chosen then the fairway bunker that is about 140 yards from the green comes into play because of how it pushed into the fairway at thatpoint, creating a small landing area after the complex between it & the cross bunker. Choices, accuray, a heroic shot rewarded... This is a pure three-shotter that will challenge everyone from the fair to the fabulous player.
These are just 2 examples of how a three-shot par-5 can be anything but dull. There are many more...