Whether you are a writer or an actor or a stage manager, you are trying to express the complications of life through a shared enterprise. That's what theatre was, always. And live performance shares that with an audience in a specific compact: the play is unfinished unless it has an audience, and they are as important as everyone else.
The point of theatre is transformation: to make an extraordinary event out of ordinary material right in front of an audience's eyes. Where the germ of the idea came from is pretty much irrelevant. What matters to every theatre maker I know is speaking clearly to the audience 'right now.'
I don't really find things funny unless they're deeply tragic at the same time. I think if you're funny just for the sake of being funny, it's just frivolous nonsense. To me, all the best comic plays have been written about really serious and rather bleak things.
Culture is something that we all share, and we are all the poorer for anyone excluded from it.
I don't think theatre has changed; it's society that has changed.