I've noticed that in a lot of situations, those who complain the most are also those unwilling to do any work to change the situation. Usually they are so good at bitching that they are unable to do anything else. But you've started a letter campain - good for you - I hope that turns the situation around.
But perhaps something more than letters are called for. Is another festival needed ? A table at the current festival so folks can sign a petition ? Can you get access to the empty field and hold a memorial singalong or jam that would be more in the spirit of the deceased ? Would a nearby club host a concert devoted to the dearly departed ones style of music ? I wish I knew more about the situation - these suggestions may be way off base. Clue us in if you can. If the situation is that dire then the facts should come out.