Wow I'm in disbelief that something so simple of an answer to the question that I've been saying for I don't know how long, is finally being figured out and recognized by people who are paid to know these things.
A lot of the reasons "sequels" to the games that sold well haven't been selling well is for the exact reason he stated. They were bad games to begin with, and after they figured it out AFTER the purchase, they aren't going to buy it again. Which is why the sequels sales have been simply atrocious.
Consumers are looking for games they are going to enjoy, and whether critically bad or just not to their tastes, they won't buy it if it is a bad game... at least after knowing it. Hell "is it a good game" is the most frequent question I'm asked at my job with "do you got that madden" at a close second ;). Nintendo products, you usually don't have to worry about that because Nintendo makes high quality games.
Bravo to Pachter for also pointing out, it isn't Nintendo's fault. Aside from controlling content, which is a bad idea, they can't do anything about it. Although, Nintendo is taking another route by putting "interest" in titles they see as "better" games such with the case of Monster Hunter 3 or Dragon Quest IX as of late. That's a definite way to counter it, because these gamers who are so disillusioned with the 3rd parties, will be less apt to back off if it has the Nintendo brand associated with it.
Only thing I think Pachter missed on, although implied when talking about Zack and Wiki, is that marketing is also the key. You can release good title after good title, but if know one knows about it then you simply rely for in-store relations. That's the other thing 3rd parties don't seem to understand, that big userbase doesn't equal sales, just sales potential. And with a system where there is numerous competition in quantity, you have to market to get yourself noticed.
It is finally nice to see someone finally saying the right thing here, instead of taking the cop out method of either blaming nintendo, the consumer, or the system.