Well, have I been wrong all these years? Because They Might Be Giants' (main) tour page now includes the following disclaimer:
Also, we enjoy having the opportunity to perform for children at our kid's shows, but there is simply no place for children at the regular TMBG shows. Things get very adult specific in terms of language. The volume is extreme even in the back of the hall, and there is usually large amounts of smoke of every variety; but most important of all-there are routinely a small number of very large, drunk, excitable adults who, at regular intervals 1.) jump off the stage directly into the crowd 2.) slam dance through the crowd 3.) throw bottles into the crowd and 4.) knock people down in their revelry. Over the years we regret to report we have seen many different kinds of serious injury due to crowd rowdiness-injury that would be far more serious to a small child than to a flexible 18 year old. There is essentially no controlling the random nature of crowds. This is why we cannot allow children at our shows. Please-get a baby-sitter. Make no mistake-TMBG shows are adult-only affairs. Do not bring children to shows that are not specifically for children. You will be turned away.
Sigh. Maybe they're right. (But I'm still sad I didn't get a chance to take my daughter to a "regular" show.)