How does metta sutra develop loving kindness

Metta sutra says "May all living beings be happy minded." This seems illogical to me as all living beings cannot be happy minded at a particular moment of time. I also feel that contemplating on anything that is false will not lead me to the ultimate truth. In my view loving kindness should be better cultivated by knowing the true nature of things because if we get insight into real nature of things then we will automatically develop kindness by clearly seeing dukkha and we would be able to understand the suffering of others in a better way. Note: I do not intend to offend great Buddhist scriptures. I asked this question to clear my ignorance.