The primary problem is still often going to be relative to the perception of the person making the complaint. I think the first step would be convincing people in this category that they're talking about matters of taste and that they do not speak for everyone in their demographic, which in this discussion would almost always be the core demographic. Likewise, there is also the problem with people becoming aggressively defensive and considering anyone that they do not like or disagree with as being representative of the "core", which is equally as bad. Nearly everyone who comes to gaming forums is core, like it or not.
I'll give you an example of what I mean.
I don't like Mario games. Never have, even though I've owned three of them, even when I was a Nintendo Power-subscribing fankid. That's a matter of taste and opinion. I've also gotten tired of platformers. They absolutely dominated gameplay during my NES/SNES years and I feel like I've played a million of them. For the most part, they do very little for me now. Again, a matter of taste and opinion. In that respect, the Wii had little draw over the PS3 or 360 for me for most of this generation--honestly, outside a few games, it wasn't until the Wii started pulling in the RPGs that I wanted one.
What I'm getting at is that I recognize that me not wanting a Wii as much as a PS3 is completely a matter of my own personal taste in gaming and not a negative reflection of the Wii itself. You can't argue taste, which people on both sides often try. The Wii has plenty of games which appeal to core gamers, it's a fact--it just might not have as many games that appeal to a *particular* core gamer. If you want to be rational about gaming disagreements, then I think that is what has to be communicated and respected by both sides.
I also think using "core" to describe games is awkward. It's a demographic term that gets confusing when used in too many different ways. I think it would be better to say something like, "the Wii has lots of games in traditional genres that appeal to many gamers in the core demographic--just not all of them." If you're a core gamer who is more interested in the FPS genre, for instance, the Wii probably isn't your first choice, and that's understandable. Likewise, if you're a core gamer who likes platforming games the most, the Wii probably is the best choice.
It's all a matter of taste and all tastes are valid.
I think that's all you really need to convince people of in order to turn most arguments into non-issues.
