In large enough numbers to make a difference? Unique music, sports, theme parks, conferences, historical attractions of significance, etc. I mean, you can't honestly think that would really move the needle, do you? Heck, as you say, it isn't like it is a chore to find a production, so what makes the Pittsburgh location even stand out? You are essentially talking about attracting an extremely niche (people who travel for the arts outside of the hubs) market, and then further targeting an even smaller niche (people who actually will travel for specific plays/playwrights of yesteryear) market, and then further targeting an even smaller niche (people who would fall into the first two categories and then choose Wilson) market to move your needle. Plus, without dedicated companies, you are essentially suggesting a quality that is indeterminable.
It is a great suggestion and surprising if it already isn't happening on a very, very regular basis already. I just don't think anyone in their right mind could think it would be a "1st rate" attraction to bring in tourism that wouldn't already be in Pittsburgh.
As it is, the Center almost closed a few years ago and went through bankruptcy and liquidation, but was saved after foreclosure, I believe, to the consortium that runs it now.