A good way to react to this, is to try to understand what makes Minecraft and Rocket League fun for him. You could ask him about this stuff, if you yourself don't get it.
And by doing that, you can maybe recommend him games that you consider to be "real" or "good", based on what tickles his brain in the same way that RL and Minecraft do.
I was playing Crazy Taxi when I was a kid (For the sake of the point, let's assume it is the same as Minecraft or RL).
If you (hypothetical "you") told me to play Policenauts or Vagrant Story, or talked to your friends about how "my son has bad taste", I would have rolled my eyes, and would just dive deeper into the stuff I'm into, and not care about your recommendations.
And if there are no other "real" games that you know that tickle his brain, people grow out of things often.
Give him time. And if he doesn't, I genuinely don't understand how your son having a lowest common denominator taste in games could bother you.
But I don't have a kid, so I will just not go further here.