Of course, I am sure that you know that The Dead were originally a Bluegrass Band. Perhaps that may be the reason that their music resonated so well with the elderly people who had never heard them before, and had no real “Rock” background. Especially “Ripple” which sounds like a Folk-song or hymn.
Just a theory.
As far as a mini-bass is concerned, I can understand why the standard sized stand-up bass would be a problem. (I play electric). I believe there is a stand-up that is slightly smaller and more manageable, but not by much.