I know that was Branagh's ambition and his mission statement when making the movie. However, even in Shakespeare's time, the intention was for the play's length to be adaptable for the needs of the venue it was playing and the audience. There was no expectation of anyone performing the entire...
I haven't watched the movie in years, but my recollection is that Williams was very hammy and Crystal was basically doing a variation of his usual comedy schtick. Many of the others (esp. Lemmon) gave very contemporary performances that clashed badly with the broad theatricality that Branagh...
Personally, I've always felt that the stunt-casting of famous movie actors who have no business doing Shakespeare was a big weakness of the film. Billy Crystal, Robin Williams, Jack Lemon, and others just seemed way out of place in this production.