Hi Tom, the first thing you should erase from your perceptions: I'm not even upset about how easy it was for notch to create compared to most games.
Get it out of your head now that it was easy for Notch to create Minecraft. The simplicity of the game does not have any bearing on how difficult it is to create games. In addition it doesn't have anything to do on the years of effort Notch (and any other successful game developer) has put in to his craft. Do a google on the 10,000 hour rule to give you an indicator.
As the Bene Gesserit mantra goes: Fear is the mind killer. It will paralyze you if you let it. You'll procrastinate while worrying about your game design and never complete anything. Forget your worries about game design. Just develop one. If it's too complex work out how to simplify it then. If the game's no good develop another one.
Don't base your life or career on what other people do. Find your own style and make that the mark of your life.