Of course, it is not true that the history plays focus entirely on the character of kings. The king's character is important (but not the entire focus of the play) in some to be sure: Richard II, Richard III, and Henry V in particular. But it isn't in either the Henry VI nor the Henry IV plays. Nor King John and Henry VIII. A lot of our thought that the king's character is important comes from the fact that the First Folio named these plays after the king of the time, even though that was not necessarily the original title they went by, and that they were all grouped together as "history plays" although the Roman history plays Julius Caesar and Antony and Cleopatra are just as historical. Even more comes from the idea that "character" is what Shakespeare's plays were all about--a Victorian notion which was forcibly grafted onto Shakespeare's work.Those histories which do focus on the king are the most popular of the history plays because in these plays Shakespeare tapped into the very human belief that history and politics can be resolved into the life and actions and character of a leader. In many Americans' minds, for example, it is their President (a kind of elected king) who is directing their politics, when in fact he does not have much power at all, except to make war, unfortunately. The belief that what is happening is all about a King, President, or Dictator makes a play like Richard II or Henry V make sense to the audience when they have a more difficult time following the complex intrigue of the Henry VI plays.