There's a reason to why publishers say that, they need to justify spending money in developing and localizing games. So basically money talk and internet petition don't.
However in case of Dragon Quest Heroes saving the series in the west is silly and unrealistic as that's a spin off and not a game in the main series.
We got Mother 1 due to sales of Mother 2 being good.
You also have to remember that Nintendo would need to justify spending money on localizing a GBA game for the Virtual console on the Wii U.
So if you want Mother 3, speak with your wallet.
Of course, I'm not arguing that we shouldn't speak with our wallets. Quite the contrary, we absolutely should. It just becomes problematic when the expectations and intentions are not clear, which is, more often than not, the case. Or, when a publisher leverages fan hope to bolster sales for quasi-related products (the Dragon Quest Heroes conundrum).
In the case of Chrono Trigger, for example, Square said that the DS port underperformed, and so, there was no demand for the series. Mind you, that version allegedly sold a million+ copies. So, uh, what exactly was the invisible demand threshold that was not met? 1.5 million? 2 million? 10 million?
In the case of Earthbound Beginnings, we will never get sales figures for it. We just have to have blind "faith" that it sells enough -- and maybe Papa Nintendo will give us Mother 3 somewhere down the line.
I am absolutely sure that there are enough people willing to buy the prerequisite number of copies necessary to green-light a Mother 3 localization, but without transparency, you get people like me that are too cynical about it. Or, you get people that drag their feet on making their purchase of Earthbound Beginnings cause life gets in the way. Or, they want to finish Witcher 3/(insert other game here) first. Or, those that own the original cart and don't feel particularly compelled to re-buy on the VC. But, if we had any sense of what qualifies as enough demand, you bet your ass those feet-draggers and fence-sitters might be coaxed into action, sooner rather than later.
Point is: this "do X and maybe Y will happen" thing is too easy to exploit.
