I had a similar occurrence at a venue a few months ago, and I have to admit that the thought of having insurance against any mishaps has never entered my head.
That said, I believe it's a two-way street and that the venue has to bear some responsibility. It's their premises they open to the public and there are inherent risks in any place where a group of people congregate; all the more so where exaggerated body movement (i.e. dancing) in situations where collision with bulky static objects (i.e. bass bins, etc.) is entirely possible.
Too many places expect the entertainer to set up in a corner of a room with no physical separation from an audience in close proximity to the "stage" area. Is it not, then, incumbent upon the venue to provide reasonable separation between performer and audience in the knowledge that there are risks involved.
The other side of the equation is that we performers take all reasonable steps and precautions to minimise those risks by keeping cables and cords securely taped down well away from the "danger zone" at the front, and that our speakers, etc., are securely mounted and positioned so as to present minimal risk to members of the audience.
I'm not a lawyer, but perhaps we have people in this forum who are in the legal fraternity or who have a clear understanding of the issues involved here. Let's hear from them on this subject.