Although the title of this passage is ‘Is it really greener on the other side?’, it is not talking about the environment or the planet we live. This passage talks about the attitudes which come from a question ‘Is half-cup of water half-empty or half-full?’. And the writer modifies the attitudes of the answers from “optimistic”and “pessimistic”to “unrealistic” and “realistic”.
In my view, I think the answers of the writer are more suitable for this question. Since using these answers are more easily show the personality of the person who answered the question. If the person said it was “realistic”which is also “pessimistic” , it means he or she can look through the world with ready for the worst things or worst situation which may happen. Of course, it does not mean the person answer “unrealistic”not ready for the negatives yet, may be they will just feel more depressed and more disappointed than the person answered “realistic”.