What is the importance of metaphysics in relation to enlightenment?

It depends on whom you ask. For some people it is part of their path, for others it is not. So there is no one-answer-fits-all.

But before we commit the sin number one in intellectual discussions let me offer a definition of enlightenment or else none of this can make any sense.

Enlightenment is the realization of our True Nature and then living as We Are, rather that as we imagine ourselves to be. And What We Are is Pure Consciousness.

The soul, the personality, this body and all of the experiences that take place appear in Consciousness. “We” are not “in” consciousness; we are not merely “conscious”. We Are Consciousness. The event of enlightenment “clarifies” that and living as We Are is devoid any doubts about that. Enlightenment well, enlightens. It sheds light on what apparently was hidden, in a peculiar, non-literal way, that is.

So, back to the original question, in my experience metaphysical knowledge allowed me to put the concept of enlightenment into perspective in the latest stages of seeking. It allowed specific false ideas about enlightenment to be eliminated therefore engendering a clearer understanding of what enlightenment is not.

Understanding what Enlightenment is is not possible; but an understanding of what it is not is extremely useful because then, the mind can stop siphoning attention or energy into false ideas and beliefs. This understanding in itself already allows a degree of inner peace, and if the inquiry is taken further may bring about the Glimpse of Truth or Spiritual Realization.

What false ideas? Can you clarify?

There are many, and different people are caught in different ones according to their spiritual education and conditioning. In my case there were three main ideas that bugged me and kept my mind spinning and the heart seeking.

One was the idea that enlightenment is equal to a higher state of consciousness. That pursuit and value, which are so common nowadays in various spiritual circles, and has been common in religions for ages, is a major one. For those who have experienced higher states particularly, that notion can be like drugs are to an addict.

That became clear to me when the Glimpse of Truth occurred. The Peace that is being sought is neither higher nor lower. Period. It is Non-Dual. But, if what we want is a “high” then states of consciousness is the way to go. A “high” is not Enlightenment.

The second notion to be destroyed was that enlightenment is equal to the evolution of the soul or that the evolution of the soul leads to enlightenment.

That is not so. Although it is correct that the soul must be prepared or ripe, and that is for any practical purposes the “evolution of the soul”.

Whatever the soul is up to, is relevant to Enlightenment only insofar as false ideas, false beliefs and certain negative emotions are absent from the present personality. Since it is the soul that determines or chooses the personality. Just like the personality chooses which clothes to wear each morning.

The soul is the dream of life in both physical and metaphysical planes and will be so long as the desire to be and to create is present. We are the Consciousness that is both the source of and the “medium” where the creation or “soul” appears. The soul is the Manifestation of Consciousness, it will not “reach” Consciousness in some imagined future.

So, discarding the notions that Liberation or Enlightenment are associated with a soul and its potential for experiences of higher states of consciousness and its dependence on time was a relief.

Another false notion was that we must be like Buddha, Jesus, Ramana or some other dead or living sage in order to "be enlightened".

If a true sage tell us that we must be like them they are likely speaking from Consciousness to Consciousness in a very particular context. 

The unripe seeker, or avid devourer of sacred scriptures, or over-emotionally inclined seeker however, can misread the message and project the Wisdom, Love, or Beauty the sage expresses onto the Sage’s personality. And from there the seeking must perdure by the force of imagination. We want to be like him or her, and that is impossible.

Buddha’s soul is completely different and much older than ours. His being and functions are unfathomable to us. Yet, his Essence is our Essence. So, we Are what Buddha is. That is what he was teaching. He was not teaching us to be “like him”. He was teaching us to be What We Are, now and everywhere. And that can only be Realized. Any projection, form or concept as a condition to Realization is false. Neti-neti. Eliminate. Get rid of false ideas and beliefs or projections of enlightenment.

There is no enlightened person. There is only the realization of Who We Truly Are. Pure  Consciousness. Formlessness. Namelessness. Simplicity. Fearlessness. Tranquility of Spirit. That is what you, I, all sages, and all seekers and non-seekers are. 

The seeker simply believes it to be otherwise in varying degrees, while for the sage that belief has been destroyed and it has not been replaced by any other belief about self. That is all there is to Enlightenment in essence. Being like ____________ (fill in the blank) is not Enlightenment. It is imagination.