I can't think of another Shakespeare play that has this much discussion of, and focus on, acting as a profession, as an art, or even as a tool.

Certainly A Midsummer Night's Dream has a play in it, just as Hamlet does, and The Tempest has the pagent that Prospero sets up for Miranda and Ferdinand, but are there others I'm forgetting? And there isn't anywhere I can think of that we get any professional actors or advice from a protagonist on how to deliver a speech.

I've certainly read critics (the best of whom was Nigel Alexander) who take the view that the play is not just a means to prove whether to take action against Claudius, but mostly an action against him in and of itself.

Hamlet tells the audience that he will use the play to prove the ghost is right, but he also says thathe will "catch the conscience of the King" with it, and he certainly does. Immediately after he has stormed out on the play, Claudius' conscience is obviously bothering him, and he tries to find redemption. The play worked well in performing that action against the king's composure.