My wife is a defense attorney specializing in accident liability. 38 years experience, long-time partner in the best firms in my area.
First, the presence or absence of insurance is not going to make you more or less of a target for a lawsuit. If you are a turnip with no material assets, then maybe you will get off the hook. But if you have material assets and decent income, and you can be even loosely connected to the claim of damage or injury, you can and probably will be named in any resulting lawsuit even if you don't have insurance.
Second, anyone in the vicinity of the accident who is in a position of authority, responsibility, or expertise can be named in a liability lawsuit even if they are only loosely connected to the accident. My wife has defended people who had absolutely nothing to do with the claim except they were a professional vendor in the area. In other words, if a guest gets hurt at the venue where you are performing, the injured person can name the venue and any vendors even remotely connected to the accident. There are few limits on who can be named in these kind of suits, and it then becomes your burden to prove you are not liable. If it directly involves your personnel or equipment, you will most certainly be named. Again, presence or absence of insurance has little to do with it, and your actual level of involvement in the accident itself has little to do with it. We live in a litigious society that has encouraged and supports this kind of lawsuit.
Finally, some venues ask that all vendors be insured for the exact reasons outlined above; to defray responsibility and liability. The more vendors who are insured, the less burden on the venue when an accident happens. For example, one of your light fixtures or a main speaker falls and injures a guest. Why should the venue be solely responsible? They shouldn't, and they have every right to expect other vendors to have some kind of liability coverage. I am also concerned about my band members being named in a suit if a guest got injured, even if my band mates had nothing to do with it. New Year's Eve we had a guest fall on the carpeted dance floor right in front of us. I think she got too close to a mic stand and tripped. Another guest further away tripped and fell, probably because of the carpeted surface (despite my warnings to the venue manager of the likelihood). Fortunately, they were both okay, but if they had been injured the venue and my entire band, individually, could have been named in any resulting lawsuit.
Beyond coverage limits, insurance companies usually also cover attorney fees and costs to defend you when you are named in a liability suit.
Professional liability coverage of up to $2,000,000.00 cost me only around $250.00 annually. Small price for me considering the fees I charge my clients. You can take a dump on insurance if you want, but being uninsured or under-insured frequently ruins lives, and that's a fact. Long-term injuries, pain and suffering, and lost earnings are no joke and quickly add up to enormous settlement amounts. People often get cleaned out and have to declare bankruptcy over it. I went without professional entertainment insurance for a long time, especially at the club/bar level, but for private/corporate/community/formal events, it's better to have it and not need it than need it and not have it.
If this is a one-off for OP, it's a personal decision he and his mates need to make, and I'd understand if they passed on the gig.