What is the wisdom behind mentioning the building of houses in Paradise in exchange for specific regular Sunnah prayers, despite the fact that the people of Paradise attain whatever they wish for and request therein?

The divine promise of building a house in Paradise for whoever prays twelve voluntary rak'ahs every day is an encouragement to perform acts of obedience and a means to enter Paradise. Whoever enters Paradise will attain all that they wish for and desire, just as Allah Almighty has promised His righteous servants what no eye has seen, no ear has heard, and no human heart has conceived.

The person of the lowest status in Paradise will be given a dominion like that of ten earthly kings, and he will have whatever his soul desires and his eye delights in. As for those of the highest status, Allah has personally planted their honor, and what has been prepared for them has not occurred to any human heart, in accordance with His Almighty saying: "So no soul knows what has been hidden for them of comfort for eyes."

Those who are steadfast in obedience to Allah are given glad tidings by the angels of Paradise, in which there is everything their souls desire and all that they ask for, and this is a hospitality from Allah, the Forgiving, the Merciful.