If Zelda sounds like it's not going to appeal to you in SS's direction? Great, if it makes you feel better. If it's the opposite however I really do think you're doing yourself more harm than good, the only kind of "boycott" I can see working, assuming you could actually get enough people on it, is avoiding any casual-ish fare that may interest you unless it ends up something like Fortune Street that IS, in fact, a game that's long been left in Japan and is only now being localized. More likely it'd work by getting people who might be interested in the casual stuff to go elsewhere, IE anyone wanting Mystery Case Files is pointed to the cheaper PC installments instead (assuming they haven't already cleared those), or getting people who want to play Mario Party to either stick with the aforementioned Fortune Street or a regular board game. Then you would, in theory, be starving them of the casual audience and thus they MUST cater to the hardcore.
More practically though? I think casual fare like that more likely helps subsidize games like Zelda, so it's really lose lose unless nothing else Nintendo puts out interests you AT ALL anymore. The only purchasing decision I can see having an overall positive effect is importing from Europe, increasing their sales, and thus indicating that stuff like this is successful enough that they really should be putting it out in North America too. I'm guessing this helped get us Demon's Souls, though Sony's looser to licensing and Atlus is more savvy on this stuff.