What are some reasons exploration was so important

Do you specifically mean the Exploration during the Age of Discovery, the geographical exploration of the world?

One is that it changed our planet forever: without it, America would look different and people would speak Quechua instead of Spanish and English perhaps!

It also changed the world's economy by 1) Columbian exchange, for example by introducing a lot of  vegetable species into Europe 2) helping us find minerals and materials needed for production

Also, it inspired us, as a community to learn about our world, and to improve our technology!