For us and for our tragedy, Here stooping to your clemency, We beg your hearing patiently.

An interesting set up.
Ophelia and Hamlet spend a few lines anticipating the long speech the Prologue is about to give, how he will explain everything.
Then the Prologue comes out and just gives them a sentence, which doesn’t explain anything.
What is Shakespeare doing here?
And what is it for?
It’s almost a comedy structure – setting up an anticipation of one thing and then delivering another.
And it is generally in the comedies that we see this trope of the nobles making fun of the players. (Of course it is usually the comedies that capitalize on the play within the play structure, as well.)
Is it all a set up for the lines that are about to follow – the one’s about the brevity of woman’s love? That could have been done without the set up, really. Hamlet and Ophelia could comment on the shortness of the prologue without first talking about how they expect it to explain everything.
And the prologue itself is not so much a prologue as it is a nursery rhyme or a fairy chant or a greeting card. It’s a little cute sing-song rhyming thing – hardly befitting the tragedy they’re actually about to share with this audience.
And it begs the question – how much of this show has Hamlet had a hand in arranging? Does he know that the prologue is going to be a sentence long and so sets himself (and Ophelia) up to be surprised by it? Did he set up the prologue to be physical rather than spoken? Is he not wanting the prologue to reveal the goods to soon? (Fat chance. They showed it all, first thing. And Claudius did nothing.) Perhaps Hamlet even wrote his prologue. We don’t know which lines he had them insert into the play. They could be these. (Though, that would be a weird choice.)
It’s all a little bit mysterious. Why such a short silly prologue? Why have a prologue at all? What is it doing in this play? Aside from giving the Players time to change their costumes and set up and such. Maybe it’s as simple as that.