Fulfilment of desires in Jannat
We are practicing in this world control over our 'excessive' desires so they do not make us weak and drive in wrong direction. In lots of situations people denied the truth and the reason cited is that they were too busy entertaining their desires so that they could not see the truth, or did not want to give up on their desires in line with the commands of God. So we should try to control our desires and reach a high spiritual point where there is nothing more important than to be in touch with God.
However as a reward the life that is promised seems to provide fulfillment of excessive desires. I mean Jannat. Whatever we wish we are supposed to get there. Although Quran does mention that people in Janna will see the face of God and may be make zikr, but this is not highlighted as much as fulfillment of desires in Jannat.
The basic expectation of the Almighty from us is that we should be obedient to Him. His obedience demands that we follow His expectations which can change from time to time and from place to place. For example, His expectations from us are different in the month of Ramadanul Mubarak than what they are in the rest of the months. Likewise when we are praying, He does not allow us to talk to each other etc. When we enter the sacred land of Makkah, there are additional expectations to follow. What He expects from men and women by way of a constrained behavior with others is relaxed in case of their spouses. And so on.
Something similar is going to happen in the Paradise. We will still remain His obedient servants, but His expectations from us would alter. Some of the pleasure-seeking acts that He dislikes in this world, He will desire from us that we go for them in the next life. He will change the rules of conduct in the next life for that life to become the life of reward. The rules of this life are meant to make it a life of trial.
One of the reasons why the next life would provide an opportunity for excessive pleasure is that those who will be rewarded with it there applied control over their inclinations to go for it in the worldly life for the sake of the Almighty. Human conscience is fashioned in a way that it protests when we do something wrong. Otherwise good and bad acts are simply acts, seemingly no different from each other. God is going to cause the expectations of the conscience in the paradise to be redone to suit the pleasure filled life of the inhabitants in it.
The paradise shall be a place of immense pleasure and contentment. Man will never want to run away from it. However, man will experience the highest level of reward there, too, in the form of God's pleasure: radiallahu anhu wa radoo anhu: God will be pleased with them and they will be pleased with God. Qur'an: 98:8