Not so long ago in India, people would get their children married at a very early age. It was common to have girls married at the age of 11 to 13 and boys at the age of 16 to 18. Obviously, there was no sense of conjugal love or marital responsibilities in either party. Most of the times the girl would remain at the home of her parents even after her marriage, and her parents and other elders would then train her in the art of managing her future household. Then on a festival day, she would be told that her husband would be visiting her and once he arrives she should welcome him lovingly and offer him a laddu (sweet). In the beginning the girl would do this as a matter of routine and would not experience any joy. She may even miss the point. But as material nature would allow her body and mind to grow, at one particular time she would blush even at the thought of that experience.
Similarly, when Krishna tells aspiring transcendentalists to offer Him something – at least a leaf, flower, fruit or water – they balk in surprise. Why would the Supreme Being be interested in such a minuscule object? Does He really enjoy these things? Well, the answer is that Krishna is full in Himself. He does not need anyone to offer Him anything because He is fully sufficient to create whatever He fancies. But being merciful, He allows us to offer Him something so that we can get purified and advance on the path of liberation and loving devotion.