As a preview ... or a quick summary: If you were to let the souls in Hell out of Hell, they would immediately start-up doing the evils which got them into Hell, in the first place. The torments of Hell teaches no damned soul a lesson. Hell exists, in order to protect you from the damned. The torments of Hell come from the damned, themselves. All that they would do is share with you the torments which is them, themselves. Hell really is "other people."
Likewise, it's the people and angels in Heaven which makes Heaven, Heaven. And, the Greatest Irony about Heaven is that, even though it is a place of purity and perfection, every time a new soul enters Heaven, it becomes a better place. The population of Heaven reflects the features of God. When enough people reflect the entirety of God's attributes and features, then the number of souls in Heaven will be fulfilled. The creation of Mankind is determined to be finite, even though each man will exist forever, be it in Heaven or in Hell.
None the less, Hell exists to protect you from the viciousness of the damned. Let us proceed: