Is the violent society of Verona the main cause of the tragic events in Romeo and Juliet?

I do believe the violence in Verona, violence that is the result of the long-standing feud between the Montague and Capulet families, is the main factor that contributes to the tragedy of the play.  First, if Romeo's and Juliet's families had not been so at odds with one another, it seems likely that they would have sanctioned the marriage between the two teenagers since the families were "alike in dignity" (Prologue, line 1).  They would not have had to hide their feelings for one another if there were not such a violent grudge between their families.  If they'd been able to be open about their relationship, then Juliet's parents never would have tried to force her to marry Paris, she would not have been made desperate, and events would not have led to her own and Romeo's deaths.

Furthermore, without the history of violence between the families, Tybalt never would have challenged Romeo, he would not have killed Mercutio, and Romeo would not have killed him.  Romeo, then, would not have been banished, and he and Juliet would not have been made desperate by being kept apart.  In short, the violence in the community that resulted from the feud between the Montagues and Capulets caused the tragedy of the story.