The game itself is just not built around losing gold when you die. In essence, you already do, becuase you miss out on at least 2 creep waves, and you've given the enemy at least 200 gold.
I don't particularly agree with your comparison of the 5/5 and 5/0, just for that reason. You may have as much gold as the olaf has (most likely not, becuase you've spent a couple minutes dead or running back at this point), but the enemy team overall has over 1000 gold more, and if they're smart, has pushed their advantage at one point to get dragon or farm more.
I personally think that gold loss upon death does nothing to add any fun into the game. It boils down to being the same as old MMO's that took experience away when you died, or other games that had severe punishments for no particular reason. Part of what I really enjoy about LoL is that the match is generally competitive till the last second, and not a lopsided victory for one side specifically because of gold loss.