At their release, options to build wedge Commander decks were few and far between, and this was the first product WotC released to support the format, obviously addressing the wedge problem
Collectors kept submitting in hopes of beating the odds
Obviously Mana Leak hits more targets than Spell Pierce, which has Negate restrictions on it, they are not directly comparable cards
You may do 120 more damage
Early in the game, you can pay a red and a black to force an opponent to discard a card
I am assuming that youre hooking it up with Rainbow Energy, of course, since P Energy is generally not a good idea in Grass decks (dont say Time Circle)