Modern audiences can relate to Much Ado About Nothing because the basic "will they or won't they" love story never gets old. At the beginning of the story, Beatrice and Benedick seem to hate each other, or at least to have a lot of tension. They insult each other both behind each other's backs and to each other's faces, and they both seem rather obsessed with each other. Then the plot begins to unfold: will Don Pedro, Leonato, Claudio, and Hero succeed in their matchmaking efforts? There are hitches and moments of hesitation where it seems like things won't work out, but they do in the end. Beatrice and Benedick are no different from the lovers of many a modern-day story whose long-unresolved tension ultimately works out into a happy relationship at the end of the show or movie.
Everyone enjoys a good love story, or at least most people do. Even if one's name is Benedick or Beatrice, one might eventually conclude that all sexual bravado, drenched in barbed innuendo, is a mere denial of latent desires. At least, that's what many critics think about the Beatrice and Benedick 'side' story.
In regard to Claudio and Hero, however, we know that 'the course of true love never did run smooth.' Modern audiences know that any good love story is filled with initial conflict which resolves itself as the story approaches denouement. Even if we have not experienced drama in our relationships, many of us probably know a couple who are definitely attracted to one another, but choose to deny this attraction. In Much Ado About Nothing, Shakespeare has chosen to address transcendent and timeless themes of gender conflict, infidelity, unrequited love, and the role of deceit in romance. As such, the sexual tension between Benedick and Beatrice is nothing new, and this tension is often highlighted in modern romances.
Additionally, the ambiguity surrounding Hero's sexual purity (due to the machinations of the sly Don John) plays upon the modern male's fear of female infidelity. In the play, Shakespeare also takes aim at the practice of deception in the context of love. When the masked Beatrice denounces Benedick to another masked man, she has no idea that the masked man she is complaining to is actually Benedick himself. Meanwhile, Don Pedro, masked himself, tries to woo Hero on Claudio's behalf. A modern audience can certainly relate to the idea of utilizing emotional masks to disguise certain perceived inadequacies from potential mates.
The relevance of Shakespeare's themes in Much Ado About Nothing is further highlighted in a number of adaptations of the play in modern cinema. Here are a few:
Joss Whedon's 2013 Much Ado About Nothing.
Kenneth Branagh's 1993 adaptation.
Dil Chahta Hai, the Bollywood version, loosely based on Much Ado About Nothing. This link also includes examples of modern movies based on the Bard's play.
With all the fanfare about romance, Much Ado About Nothing certainly lays bare all the maddeningly delicious challenges the pursuit of love entails in our modern world.