I omit all speculation as to the form which the story assumed in the Ur-Hamlet. We have no evidence on the point; and, as the poet was no doubt free to remodel the material as he thought fit, even in following his original he was making a deliberate artistic choice.
Shakespeare committed it in Romeo and Juliet, where he made Friar Laurence, in the concluding scene, retell the whole story of the tragedy. Even in so early a play, such a manifest redundancy seems unaccountable. A narrative of things already seen may, of course, be a trait of character in the person delivering it; but, in that case, it will generally be mendacious (for instance, Falstaff and the men in buckram). Or it may be introduced for the sake of its effect upon the characters to whom the narration is addressed. But in these cases its purpose is no longer to convey information to the audience--it belongs, not to the "intelligence department," but to the department of analysis.
I say "variety" rather than complexity because I take it that the emotions of all concerned are here too intense to be very complex. The effect of the scene would appear to lie in the rapidly increasing intensity of comparatively simple emotions in Hamlet, in the King, in the Queen, and in the amazed and bewildered courtiers.
This excludes Love's Comedy, Brand, Peer Gynt, and Emperor and Galilean.
See, for example, King Henry VIII, Act IV, and the opening scene of Tennyson's Queen Mary.