Theres a few things going on here.
First, a good precursor to this discussion is (and this seems to happen a lot) watching an episode of Extra Credits. Namely, Graphics versus Aesthetics. Criticizing a game for its Aesthetics is fine. Poor Graphics can reflect poorly on Aestetics in some instances, and under some tastes. Criticizing a blank, lifeless game based on appearances is fine, and its reasonable to not like a game with poor Graphics simply because your no longer able to appreciate the Aestetics when rendered so primitively (Though this comes down more to taste then a proper critique). What I'm interpreting this question as is those individuals who judge an entire game based on the polygon count, texture quality, and other technical merits.
This approach is not something I'm willing to dismiss. If it's something people feel about how they enjoy a game, who are any of us to say that they are just wrong? For people who value graphics above all else, video games are toys. They are funny electronic gadgets full of bright colors and mindless distractions. They just don't appreciate the depth games have to offer. Sure, it's tempting to lament this as a huge loss on there part, but then again, though I like Jazz, I rarely listen to anything beyond some occasional Miles Davis. I can appreciate a true connisuer of the art, but I'm just not going to dive that deeply into it.
Of course, this leaves the game enthusiast in an odd place. You can't agree with the people who don't like Minecraft because it lacks polygons, but you also can't bash them for being uncultured philistines when they are still having a good deal of fun in a medium where fun is an excellent goal. You have to strike just the right balance of live-and-let-live versus deeper-then-though. Make a tongue in cheek argument against something they are particularly interested in. Point out that there is a lot more to games then polygons, an entire world that they simply fail to appreciate, but they don't necessarily have to appreciate. Sure, they fail to appreciate the power of games, but no one ever said that you HAVE to appreciate the power of games.