Inventing your own story world helps you see things in our own world in a different light as you perhaps work out how to bring these things into your fictional creation. How would they govern themselves? Multi-party democracy as in the UK or a one party state? Are there political parties at all? How do people get into power in your fictional world? And that's just one example. The more you flesh things out, based on knowledge of what happens on Earth, the more real your fictional world will seem and the more accurately you will write about it. Your readers have to be convinced by your world and the first person to convince is yourself. Does your fictional world seem real to you?
Bringing in Things You'd Like to See on Earth at some stage
Conversely you can put things into your own world that are not happening on Earth at the moment. You can work out how your ideas would work out.
The Joy of Creation
There's nothing to beat this. I always get a thrill as more of my fictional world comes to life and it seems real to me.