Telephone surveys have a moderate cost, and they are fast. Of course, there are other ways to elicit quantitative information besides surveys, such as experiments and observation, but we'll stick with this most popular approach. That's why most surveys either provide the answers or furnish the scale on which to rate specific responses. They're easy to administer, quick to score, and easy to understand. But they do reduce the richness and variability of the responses.
Some surveys use a combination of both types of questions.
Good questions are difficult to write, but seem easy. Because most people will create questions that have a hidden bias which can skew the results. For detailed advice on how to do write good questions, consult a book or articles on consumer research. One good book is How to Conduct Your Own Survey by Priscilla Salant. The major problems with questions center around unintended bias and clarity.