Look at the Bethpage Black holes. The 7th has nothing coming into play at lay-up distance. It is a two-shot hole. You may have to roll it up there, but you can reach it. Furthermore there is little second-shot/third-shot strategy.
The 4th, a shorter par 5, cuts off the first fairway, forcing you into a second shot up to a natural layup area or to the elevated green (which sheds shots in all directions - over, or in the deep traps or rough). So the smart play is off to the right of the green, and you have the same (3rd) shot except from the fairway instead of nasty sand or grass.
That three-step approach to the hole makes the shorter 4th into a par 5, while the longer 7th remains a par 4.