Or, "He's dead guys, what does he care about fashion?"
Barbarian PC: "I charge & attempt to grapple the lich!"
Me: "Roll me some Fort saves..."
Of course, at level 18, most of them will make DC:15 Fort saves in their sleep.
While that is true, there are ways to drop their save bonuses.
But the real reason to do it is to disrupt their thought processes. Its a surprise- potentially a nasty one if someone rolls a "1"- and it will make them rethink their tactics...especially if they don't know they're rolling against DC:15 or why they're doing it. If all they know is that Brak the Barbarian had to make 3-5 Fort rolls- which he probably succeeds at doing- just grappling the Lich, they'll still have a "WHOA!" reaction.
Any ACTUAL result from the "Sweater O Doom" is just gravy.