Rebelling God is the cause of evil. To create a perfect heaven, he needs to completely destroy evil and to stop evil from being recreated. God's purpose is to create a perfect heaven. He knows that evil is the result of rebelling (disobeying) him. Being all-knowing, he knows that the only way to make a perfect heaven (prevent God rebellious soul) is to let us experience the consequences of rebelling him, that's the sufferings caused by sins.
That's why we were sent here, a temporary earth, temporary life, where evil rules. All the faults that we commonly find against God are infact our saviors, the consequences that make us elligible for eternal life. The consequences that make us love him, submit to him eternally in heaven. We know the theory about action A causes action B, our experiences determine our destiny.
How to create a perfect heaven? We are all living in the process of making a perfect heaven. One possibility is the use of pre-emptive process. Since God is all-knowing and timeless, he can just work to and fro between times. All things happening now affect our future occurances. God is actively working to allow more souls (who will not rebel against him) into heaven. He can even bar those souls who cannot be saved, who are destined to commit sins in heaven.
A pre-emptive process of making a perfect heaven. If it's right, it explains why some believe in Christ, some don't. It explains our sufferings, and why some Christians have to suffer, and some don't. It explains Christian faith, God's hidden nature, etc. Like it says, things happen for good, for God's purpose.
All souls who finally enter into heaven will not rebel God eternally. Free will, and at the same time, they are the works of our all-knowing and loving God. That's why it was written; all souls will praise him eternally in heaven.
So, what is needed in heaven is the 2 greatest commandments; love God and love our neighbours, and heaven will remain perfect eternally. If we love God, we will never rebel him and hence evil will never be recreated. If we love our neighbours, all souls will live in harmony with one another. Perhaps this is what Jesus means; these 2 commandments replace all other commandments.