What are the advantages of performing such meditations?

It is mentioned in Mettanisansa Sutta in Anguttara Nikaya that the loving-kindness meditation has eleven auspicious outcomes. They are, having a good sleep, waking up well, dreaming no nightmares, becoming pleasant for humans, prevention of harms by demons, protection of deities, life without any harms from fire, poison, or weapons, attainment of mind concentration quickly when meditating, a beautiful face, a good death without losing the mind, a birth in a world of higher-level beings called ‘Babhalowa’ if the Nibbana was not realized in this life.