Being debt free can sometimes be based more on emotional money management than overall smart money management.
i.e. We've not yet paid fully for our 10 year old RV that we bought new. It's part of a loan on our home that started out as a 2.7% variable rate 2nd loan that we later converted to a 30 year 1st loan at only a slightly higher fixed rate. We could have paid cash for the rig, but will earn more over the long run on that cash than the low rate loan will cost.
Also, our home is worth far more than the loan against it that paid for the RV ... so having a small loan against it (relative to it's value when we sell it in our extreme old age) is well worth any feelings of insecurity that we might have, but do not have, from not being debt free. We consider this approach as rational money management as opposed to "debt free at all cost" money management. :)