None. There is no good reason why Mother 3 never came to America.
Oh, there are a couple of valid reasons why we never officially received Earthbound's follow-up, but they're not necessarily good.
The easiest blame can be laid on finances. We are elbow-deep in the era of the Nintendo DS right now and the heyday of the Game Boy Advance is long over. Nintendo might get away with releasing all three Mother games in a DS collection, but that's obviously not going to happen in a grand hurry.
By now, the universe knows that the original Earthbound bombed on the Super Nintendo. Nintendo did a beautiful, loving job with the packaging and translation, but dropped the marketing ball hard enough to cannonball clear to China. Earthbound was marketed as a cheesy science fiction game brimming with toilet humour, which it wasn't. Alas, a mass-mailing of scratch-and-sniff stickers made to smell like rancid pizza will do a lot to kill an appetite for game.
Besides, after experiencing the majesty of Final Fantasy VI and Chrono Trigger, why would anyone want to fight against giant piles of barf? I sure didn't. Earthbound tanked, Nintendo made up their mind about American tastes and Mother 3 never had a chance at a ticket to America.
Since the release of the translation patch, however, more than one person has claimed that maybe Nintendo's fear of another financial disaster wasn't the only thing keeping Mother 3 from the States. There was suddenly talk about in-game content being inappropriate for American audiences: the dark story, the characters (oh, the characters) and whatnot. God knows Japan has thousands of little quirks that only those born under its flag can truly appreciate, but I don't see how Mother 3 is one of them.
Mother 3 is certainly unorthodox. Much like big brother Earthbound, it adheres to basic JRPG battle rules, but its heart and soul are wholly unique. The game ladels endless charm over the player, but at the same time, the story is unapologetically sad and says a lot about our tendency to listen to shit-disturbers disguised as charmers instead of making our own sane judgements.
American gamers could do with a story as raw as Mother 3's. It's not what we're used to, but that shouldn't matter. Before I inevitably die under a falling safe, I want to see game stories earn recognition as true literature. Unless games like Mother 3 reach a wide audience--games that have stories worth listening to--that's not going to happen.
Mother 3's other damning trait, the townspeople say, is its questionable content. The strongest example cited thus far are the magypsies, an immortal, all-knowing and all-powerful troupe of...er, transvestites who aid Lucas and his friends in saving the world. This makes for interesting times. Lucas, for instance (PSSST, MILD SPOILERS), has his PSI powers awakened through a questionable encounter with a naked magypsy in a hot tub.
Even this particular scene isn't close to explicit. It certainly implies that black-screen hot tub shenanigans went on between Lucas and the magypsy, but only in that coy, joking way that happens all the time in anime, games and manga. When the picture comes into focus again, it becomes obvious Lucas' head was being held underwater to awaken latent powers vital to his survival--also an extremely common occurrence in anime and manga. The entire scene wouldn't be too difficult to censor, though it would be unfortunate.
(End spoilers, babe.)
Now, I'm probably just talking out of my proud, firm buttocks because I'm only about halfway through the game. But so far, I'm comfortable saying that Nintendo never released Mother 3 because they're still throwing a profit sulk. They could take a chance on Mother 3, which could easily get away with a Teen rating, but they're a business and must step carefully. If game companies didn't have to think about profits and made games solely to lighten the hearts of fans, we would have had Mega Man Legends 3 by now.
It's a shame, because the whole world deserves Mother 3.
(And now we have it either way. Heh heh.)
Related Links:
Mother 3 Makes Me Feel Human Again
What I'm Playing This Weekend: Mother 3. Doi.
The Mother 3 Strategy Guide: Fandom Done Right