Suppose you were a biologist studying and trying to understand a flower - possibly tulips. And suppose also that you could ONLY detect things that were green. Look at the below image of a field. This is what it would resemble if you could only see green. Try running your mouse over the image.
Flowers are an important part of a plant and are in fact one way they reproduce themselves.
We could probably not see plant roots either, which would hinder us from learning how plants get nutrition. There would be large gaps in our knowledge of plants and how they work. A similar situation exists in astronomy. Because we can't see X-rays, we had no way of knowing this until we thought to look at the skies with electronic eyes. Seeing only green gives us a very incomplete, and even incorrect, picture of things around us.