] Are there other reasons why Hamlet has spends so much time on acting?

I've always felt that one of the reasons Hamlet dwelt so much on professional acting was because Shakespeare did. Doesn't some of his instructions to the Players seem like a critique on the theatre of his time?

Speak the speech, I pray you, as I pronounced it to
you, trippingly on the tongue: but if you mouth it, as many of your players do, I had as lief the town-crier spoke my lines.

O, it offends me to the soul to hear a robustious
periwig-pated fellow tear a passion to tatters,

suit the action to the word, the word to the action;

O, there be players that I have seen play, and heard others
praise, and that highly,... have so strutted and bellowed that ... they imitated humanity so abominably.

And let those that play your clowns speak no more than is set down for them;

Can't you see him saying that last one to Burbridge? ;-)