It's an interesting question, because the increase in the number of venues could affect ticket prices in a number of ways.
First, the venues compete with one another to book talent, in which case more venues (or at least more venue owners--LiveNation likely doesn't compete with itself) might mean more money paid from venues to talent, which could drive ticket prices up.
But on the other hand, more venues booking more overall shows should drive ticket prices down, as the shows have to compete with one another for the ticket buyer's dollar.
Finally, if there are lots of venues booking lots of shows and buying lots of ads trying to get people out to shows, an increase in venues could drive overall consumer demand higher--in short, the city becomes a hotter place for live music--which is why some cities seem to get a lot of shows relative to their population and others don't.
I'd be interested to know how Seth thinks this has shaken out over the past 10 years or so.
But then again, I'm a geek.