"It's not that it's unchallenging, but, by removing length, it does present a diminished challenge."
So more length is inherently more challenging? I thought that notion was taboo on this forum.
Secondly, there has to be a preference of some sort by designers. Actions imply that a choice was made, and that choice more than likely was made for a reason, logical or illogical, right or wrong. But there is a choice made when it comes to how a golf course is concluded, whether it goes to the top of a knob, or to the bottom of a hollow, whether it turns left of right, and yes, whether it is a long par 5, or a driveable par 4. And more than this, the fact that almost no one ends a course with a driveable par 4 does suggest that there is a preference against it, and I would posit that this reason is more than either difficulty, match vs medal play, or television.
And finally, "If the match was over before the competitors reached the 18th tee. no one would care about the 18th hole. And, most matches are over before the competitors reach the 18th hole."
So why have 18 hole golf courses at all? In fact, that's a preference in itself, to build 18 holes. Any developer or designer could just as easily choose to build only 14, or 23. It's unconventional, to be sure, but there is no rule to say that a golf course must be 18 holes; it's more of an widely accepted norm than anything.