As we wouldn’t chant “Papa, papa” if we wanted a chocolate from our father, why should we chant “Krishna, Krishna” if we want something from him?
The actual purpose of chanting the names of God is not to ask something from him, but to awaken our love for him.
We are the children of God, but we have forgotten this because we are suffering from spiritual amnesia or forgetfulness. Hum bhagavan ke khoye huye bacche hai.2 For curing amnesia, patients are often exposed repeatedly to stimuli from their forgotten life. So for curing our spiritual amnesia, we need to expose ourselves repeatedly to spiritual stimuli. The most potent of all such stimuli is the holy name of God because God is our closest spiritual relative. So chanting his names repeatedly is the most powerful treatment. Thus the scriptures recommend chanting because they want to cure our spiritual amnesia.
However, most of us are not interested in that cure; we are interested only in worldly things. So to induce us to chant, the scriptures also promise that our worldly desires will be fulfilled by chanting. This promise is like the promise of parents to their children that they will get a sweet if they take a medicine.
Initially when we approach God at the levels of fear and desire, we chant because we want something from him. Later, as we learn about the level of love by education and rise towards it, then we
2 We are the lost children of God. chant to awaken our love for him. And finally when we truly love God, then we chant because it helps us to easily remember our beloved.