With all due respect to your studies, there's something here that seems to fail a basic Occam's Razor test.
You say that one of the primary reasons adults like fantasy is to recapture this wonder that they have lost.
But children, from the time they learn to use words on up, also like fantasy - Dragons and unicorns, knights and princesses, these are the bread and butter of children's dreams, right? But they are incapable of a desire to recapture the wonder, as they haven't lost it yet. Whatever reason they have for liking fantasy, it isn't recapturing lost wonder.
Occam's Razor says we should not multiply entities when we don't need to. Why do we need a reason beyond the child's (whatever it is) to explain the interest in fantasy?
Or, to put another way - why aren't we talking about a human reason for interest in fantasy. Why separate ones for children and adults?
I like your line of thinking here. Actually, I would say that in a healthier culture than our own the interest in fantasy and imagination would never cease. But in our culture it is generally seen as childish or at least "fringe". Over the last few decades this has begun to change, fortunately.
Why separate children and adults? Because children and adults are fundamentally different. Certainly an adult can include their child-self--just as a nine-year old is still an eight-year old, but with an added year, and with all that entails. But what makes a nine-year old different than an eight-year old? Not a lot but there
is something new, something emergent within the ninth year (as an example). A child's experience of reality is very different than an adult's. I think adults often lose sight of this.
So I would continue on with your point by saying there is a spectrum of experience in relationship to fantasy and imagination. Some continue to nourish and develop it, some don't (they "grow up").
The reason that adults need to "re-capture" lost wonder is because they, unlike children, have lost it, at least to some degree. Now for RPG players this is a bit different, but I think it still exists as an outlet, and is perhaps part of the reason people keep on playing. I find it culturally interesting, actually, that RPG players keep on playing, by and large, indefinitely (who knows who will still be playing in their 70s and 80s? RPGs have only been around for, what, 35 years?). Sure, there are tons of people that play a bit in middle school or college then stop and never play again. But for serious fans, once they start they never stop--or if they stop they come back. I think this has something to do with it being an outlet of not only fun, but wonder.
When I say that adults have lost their child-like wonder I don't mean to say that they (we) have completely lost it, but that it becomes less of a pervasive experience and more rarified (again, I'm talking about people in general, not the exceptions to the rule). Our perspective of the world broadens, becomes more complex. S'mon misunderstood what I meant by "Fall" when he equated it narrowly with Biblical Original Sin. The "Fall" occurs in many ways, in different contexts--it is more of a symbol with mult-faceted meanings than a narrow allegory.
We "Fall" when we realize how pervasive suffering is, or when we realize that life isn't what we thought it would be, or even earlier when we realize that we are going to die. The Fall(s) isn't even a negative thing--actually, it is a birth into a wider world. It is just that a lot can be lost, be left behind, be replaced and never found again.
If we're talking about a human reason for fantasy, I think there are many--including the desire of being "filled with wonder", the mystical experience David Zindell talks about as synonymous with a sense of divinity. This isn't why people like rolling dice but it does have something to do, I think, with why people like Story, why people are drawn to magic, mystery, hidden secrets and lost civilizations. It is a kind of tantalization of the mind, like something forever out of reach but pervasive at the same time.
I'm not sure if that addressed your point?
). I would argue that sexuality exists even from early on in some form or another, with various stages of activity and latency (Freud goes into this stuff ad nauseum; I don't agree with everything he said about it, but at the least he brought this forward). But puberty is a biological fact, and sexuality doesn't really "awaken" until puberty starts, at least not with such intensity. I would even say that there are possible later stages of sexuality beyond maturation that the vast majority of people never really dive into. 
