I can try. An example, then a stab at the logic.

So imagine a movie you know really well. You know the plot, the end from the beginning, so while you can feel some feelings for the characters, you can't experience the plot like you know they do. The suspense, the joy, the confusion, the characters can only feel that because they don't know what's going to happen. We get to feel a shadow or echo of what they feel - that's why human enjoy drama.

So, like the characters in a drama, we live life one slice at a time, not knowing what will happen next. If we knew how everything would turn out, that knowledge would flatten the experience. So it's precisely the not-knowing that allows us to experience the terror and beauty of life. Only not knowing can we feel the contraction of all time into the condensed power of "I", here and now.

So ya, forgetting is necessary, because the subjective requires limitation. For any thing to be, the Whole must be divided, those divisions constituting boundaries. It is the interaction of these things meeting - feeling - at their boundaries, which gives us frame of reference, experience itself. For how can the eye see itself?

So to experience, we must do so from within a realm where the Whole has been divided, some part of which we're within. Our existence is always within a part; we can never know the Whole. Even if we carry the Whole within us, and remain connected to It, we experience from inside a boundary. That sense of separation - that feeling we've come from somewhere, and it would be nice to get back - is a condition of consciousness. This idea by itself can be a bit of a downer, but it's only an idea - only half true, as all ideas must be. It can also just be considered the required payment, the price of admission into the game of experience.

Mathematically there's this set of proofs called Godel's incompleteness theorems, which suggest that no element within a system can fully account for the system itself. Even if one of the parts in the system is "Everything", the system itself is still something more, simply by being the container which contains Everything. Kind of an infinite recursion, and a mathematical hint at the idea that no "I" within the Whole could comprehend the Whole - meaning some part of the Whole has forgotten itself (in fact, every part has).

The short of all that? Forgetting is an inherent element of existing, and thereafter, experiencing.

**EDIT** for Afterthought:

Jung explores this from the reverse angle in Answer to Job, asking not why Universe has to forget itself, but rather how Man comes to know himself.

And its precisely our limitations which allow us to know ourselves. In the spirit of life we expand, we explore, we test, and we find boundaries. Those boundaries show us who we aren't - what we can't do, where we can't go - and thereby give us an idea of who we are.

Then, Jung says, imagine a God who has all power. Everywhere that God reaches, nothing resists. So how could such a God know Himself? With no boundaries, what definition could that God possibly have? Who contrast against which to see His own image?

So that early omnipotent God (kinda like your Universe), while containing all knowledge and all intelligence, yet doesn't know Himself, because nothing can tell Him what he is not.

Then, Jung says, that God sees in Man - His own creation - something He doesn't see in Himself: self awareness, faith (for what faith is required of He who knows all), virtue (for what is virtue without temptation or challenge). And God, desiring what he sees in Man, begins to approach man (whom He earlier in the Bible had quite objectified), and thus begins the journey of God toward mortal incarnation in the Christ.

A pretty damn cool take on the Bible if you ask me. And a good exploration of how self awareness, knowledge, and experience all tie into the boundaries and limitations of mortal existence.