Who is it that decided that a character in an RPG who is extraordinarily lucky should have that luck modeled by re-rolling dice?
I know that White Wolf did this - both in their World of Darkness games (in which Luck was a Merit) and in Aberrant (in which it was a power). I am fairly certain that I saw it that way before, though.
Recently, D&D released their Complete Scoundrel book, which includes Luck Feats, which are essentially feats that allow re-rolls in particular instances.
I understand that re-rolling dice models luckiness on the player's level. To me, though, this doesn't translate to luckiness on the part of the character. When you have an available re-roll, you tend to use it in order to counter an unusually bad roll. What does this mean to the character, though? It means that the character is more consistent than other characters. Does consistency equal luck? Not so much.
When I think about someone who is unusually lucky, I think of the person who makes that one-in-a-million shot. Twice. I think of someone who wins the lottery... with a ticket that she found on the sidewalk. I think of someone who succeeds due to chance occurrences in the environment. A lucky warrior doesn't defeat the orc barbarian because he gets to re-roll his failed attack. He defeats him because the orc trips over a fallen branch and impales himself on the warrior's sword.
Re-rolls don't do it for me.
To some degree, this can be solved by description. If, when you successfully use a luck re-roll, it is described as something truly lucky happening rather than you simply succeeding where you otherwise wouldn't, then you can at least maintain some of the flavor of luck. This still rarely models good luck that results in miraculous benefit, though. I mean, you might skewer the orc instead of yourself, but you aren't going to find a winning lottery ticket.
Is there a better solution? In part it matters how you conceive of luck in your world. Sometimes, luck is conceived of as a limited resource: someone lucky might push their luck too much and either run out or even end up with bad luck for some time. Personally, I like to see luck be less mechanical and more descriptive.