I just skimmed the thread so I am sorry if this has already been said (if it hasn't I'm surprised)...
One NEEDS a credit card. At Least open it, pay it off in a full each time the bill comes in to prove that you CAN make payments, and then let it go.
Chances are, you WILL need credit. My husband does finance for a living and deals with a ton of people who use cash only. That's a great system- we don't finance anything either unless we get rewards that are amazingly worth it, and then we pay it off each month.
You may have GREAT credit-- but you probably have no credit history. You may have one or two things showing on your bureau- but honestly-- with the best of scores that might not get you financed if you really needed to. You must have good ongoing credit history.
I suggest opening a credit card (not a debit card)... and putting a few things on it that you would normally already purchase, and paying it off every month. You need this, I PROMISE.
Dh's grandmother has EXCELLENT credit- she is in her 70's.... but only ONE bank can finance her because she lacks enough credit. She has maybe one or two things... you need MANY. You need to prove to these companies that you aren't in good standing just on one or two transactions-- but that you are consistent each and every time. They don't care that you pay for your cars and houses in cash (which is GREAT by the way)... they care that you pay borrowed money back well.
Again, I think its WONDERFUL that people pay cash for things... DH and I do this too. But having credit in this day is very important. Things can happen in life that can make a very stable environment very shaky (deathly illness/hospital bills, loss of a job, etc). You may not ever need your credit (and I hope you don't)-- but let it be there to fall on just in case you ever do!
I did just want to add that credit cards are not the ONLY way to build your credit-- but they are the fastest way (esp. since you haven't ever had one). It is also a great way to ESTABLISH credit (if you have NONE). Wait until you get a credit card offer in the mail and have someone sign on with you that has credit-- make those payments in full every month and you have suddenly established credit.