What were Shakespeare's tragic plays, and why did he write them?

Shakespeare wrote a plethora of different plays. He wrote in three categories; comedies, tragedies, and histories. The category that I am most interested in, however, are his tragedies. So, my topic question is, why did Shakespeare write tragedies?
Shakespeare’s tragedies included: Romeo and Juliet, Julius Caeser, King Lear, Hamlet, Macbeth, Othello, Antony and Cleopatra, Coriolanus, The History of Troilus and Cressida, The Life of Timon and of Athens, and last, Titus Andronicus. Two other plays were considered tragedies as well, but were also considered romance by other people; Cymbeline and Richard II. Shakespeare’s plays were connected to Aristotle’s perception of tragedy; the character must be well liked, but also capable of making mistakes, and the audience must sympathize with the characters. His characters were also capable of being good or evil, and had the free will to back out of anything whenever they liked.
Shakespeare wrote tragedies because he thought that other tragic plots that English writers wrote were lacking in plot. Most of his tragedies included a main character that usually died or had something bad happen. He also included suspense and climax to attract more attention. Also in his tragedies, the main character, or hero, was usually a wealthy nobleman. He was usually well in society, and possessed some flaws that contributed to his downfall. There were also evil agents that helped plot the downfall.
The most popular tragedies written by Shakespeare were:
Hamlet: About an emotionally scarred man that wants to avenge the murder of his father, the king.
Othello: About a general in the military in Venice is victimized because of his love for the daughter of a venetian statesman
Macbeth: About a noble warrior that gets caught up in a struggle of power.
King Lear: About an old man’s descent into madness as the world around him crumbles