We all grew up listening to jazz, like Miles, Mingus and Monk. And we were into the fusion sound with Herbie Hancock and the Headhunters, Mahavishnu, Weather Report and so on. At the same time we were into all that we were listening to The Dead and then Phish and Widespread. Being a jam band allows you to incorporate a lot of different styles of music, like jazz, in an accessible format. People can sit there and sing along with a song, and have it mean something to them, and we can still express ourselves in a very free form.
Most jam bands can jump from style to style, which is very freeing musically.
I see it as coming from people who have a stereotyped idea of jam bands. A lot of people have been bored at pretty mediocre jam band shows where the musicians weren't at a certain level of excellence. That can be tedious. Listeners who've been burned may have made up their minds that all jam bands sounded like that. That can be pretty closed-minded.