Because it made it more interesting. Or because that was where the story was set in his source. If he wanted to write a play around the story of Hamlet Prince of Denmark, he could hardly set it in England.
Shakespeare got most of his plots from earlier plays, stories and poems, and he quite often kept the setting of those stories. Hamlet, for example, is a story which had always been set in Denmark. His source for Romeo and Juliet, Brooke's poem Romeus and Juliet, was also set in Italy.
Thirteen of Shakespeare's plays were set or partly set in England, which was not a foreign country to Shakespeare . That is more than a quarter of them. The fact is that Shakespeare tended to set his plays where they were set in the sources he got them from. And Shakespeare used a lot of sources which were derived from Italian stories or classical stories which were set in Italy or ancient Rome or Ancient Greece. The only plays which are not at least partly set in Italy, Greece or England are As You Like It (France), Hamlet (Denmark), and Measure for Measure (Austria).
He would not have been able to make a living as an actor and playwright in Stratford. He had to go to London where the professional theaters were, just as a young person today has to go to New York or LA to make a living as an actor or playwright. He may have left Stratford touring with The Queens Men, joining them when they were on tour in Stratford.
In my opinion it has to do with two factors:
However, he did set ten history plays full of shocking murders and misbehaving royalty in England, so that was ok, just so long as the misbehaving royalty in question was not the current monarch or his or her near relatives.
He also did set one play, The Merry Wives of Windsor, which is full of stupid and silly people, in contemporary England, and it was reasonably popular (especially because of the presence of Falstaff in it). But that was the only time he set a play contemporaneously.
Another factor worth considering is:
He didn't always. The names and places in the history plays were familiar to Englishmen. One play, The Merry Wives of Windsor, takes place in contemporary England, and the characters have such prosaic names as Mrs. Page and Mrs. Ford.
Where the plays are set elsewhere, this is often because that is where they were set in the sources Shakespeare got his story from. This is true of Hamlet and Romeo and Juliet.
Sometimes people are given names which give you a clue as to what kind of person they are. My favourite is the name Supervacuo from Thomas Middleton's play The Revenger's Tragedy. The names Subtle and Face in Ben Jonson's The Alchemist are like this. Shakespeare used this kind of name less, but there are such characters as Mouldy, and Slender, and Shallow, as well as Bottom, who gets turned into an ass.
Because Poms are boring, whinging bastards
Shakespeare wrote his plays between 1590 and 1613.
Yes he did.
Shakespeare wrote a lot of plays - here are some of his more well known characters: Hamlet, Ophelia, King Lear
Yes Shakespeare's plays were written in verses.
Shakespeare wrote Shakespeare's plays. Other theories may be entertaining but have no evidence to support them.
Do you mean "places"? Or plays?
Shakespeare wrote his plays between 1590 and 1613.
Yes he did.
All of Shakespeare's plays were dramas, so here are the names of two of them: Cymbeline and Timon of Athens.
Shakespeare wrote a lot of plays - here are some of his more well known characters: Hamlet, Ophelia, King Lear
Shakespeare wrote thirty-eight plays, not six. See the related question to see the thirty-six plays.
All but two of the moons of Uranus have names drawn from Shakespeare's plays. Many of them are taken from The Tempest, and most others are names of young female characters from the other plays. The two moon names not in Shakespeare are Umbriel and Belinda from Pope's The Rape of the Lock. The name Ariel is in both this and Shakespeare's Tempest. The two largest moons are named for Titania and Oberon, king and queen of the fairies in A Midsummer Night's Dream.
Shakespeare wrote 38 plays.
The Plays of William Shakespeare was created in 1765.
Yes Shakespeare's plays were written in verses.
Shakespeare wrote Shakespeare's plays. Other theories may be entertaining but have no evidence to support them.
William Shakespeare