Well, most people, if they move, tend to "move up" and, unless they have the necessary liquid funds for the difference between the sold price (less taxes, fees, and broker commision) of the old house and the buying price of the new house, you will need a loan. Generally speaking, the better your credit score, the better the loan (lower interest rates) you will get.
If you are willing to run completely off the credit grid your entire life, then you have no need for a good credit score.
Definitely! As I said, use your credit, don't abuse it. Put another way; "live with credit but not on credit".