Why is a good question to ask. Should we not present our best face to the world? What is Rumi saying about it to us? This is a comment that can be contemplated on many different levels. First could be social level, we should not be two faced is clear enough but also, if we keep hiding our true self and live in constant fear of how will everybody like us, we never get to grow and experience life from our point of view. Allah has created us with our own point of view and we must experience Allah from our own experiences. If we act according to how others might like us to be is suppressing our own inner
self and stopping the growth.
Another level of contemplation could be the spiritual, either be one with your essence, which is Allah. Since our true and everlasting self is the spirit of us, if we do not honor this spirit and acknowledge it, we will be the ones losing out on a big opportunity of being one with Allah. The purpose of this journey in this planet is to consciously make a trip back to Allah and earn our nearness to Allah. As Sufis, we want to cleanse our nafs [ego] and be one with Allah here in this world, otherwise at the end, everything will be facing Allah when we die or when the world finally ends. Why wait? Rumi says, make a decision, choose Allah. For him, he never had any question about this issue. He chose his path to honor Allah and here he is the most read poet of our times, a caller of hearts to the Divine.