It depends, if you only focus on graphics, it will be less fun. What you need is a balance. Some games are so fun even with bad graphics. For example packman or Mario. Also like Minecraft, if you put shaders, it will get a bit boring even the game you are playing is same. (If you are talking about real life graphics )
In simulations, you need to make sure the same scene isn't loading 100 times. There must be something even a little bit unique element. In real life simulations, may be you can change the environment a bit, or lighting or even the weather. That creates a big difference. (If you are talking about real life realism)