One thing that has changed over time is the recipe for recoupment. For musicals, the length of time they need to run to recoup has increased, which means they need to cater to a broader audience to run for that length of time. And that means catering to tourists to some extent.
For plays, the current recipe of very short runs with big stars in revivals is relatively new. Of course, the general concept has always existed, but it seems that almost every play revival (and many new plays) is only planned to have about a 3 or 4-month run, which is shorter than in the past. And, outside the non-profits, these short runs often seem to be produced with a tourist audience in mind.
There's a bit of a vicious circle here with the plays. Costs are higher, so ticket prices are higher, so a show has to be an easier sell to get someone to pay the higher prices, so that involves stars who might not want to commit to longer runs, so the costs are higher and there is a shorter time to recoup, so ticket prices are higher, etc, etc. I personally find the trend to be very concerning, but I'm not sure it's going to stop any time soon.
"What was the name of that cheese that I like?"
"you can't run away forever...but there's nothing wrong with getting a good head start"
"well I hope and I pray, that maybe someday, you'll walk in the room with my heart"