I was watching a mildly humorous retelling of harry potter last night, narrated by an 'alcoholic wizard'. The whole film is on youtube, this is just chapter 9.
Amusing narrations aside, it fascinates me how harry potter, and others- Discworld, Middle Earth, Azeroth etc are those exciting fantasy worlds people get so entranced and absorbed by. It can be so absorbing that people will happily spend their wages on fake encyclopedias, maps and even cookbooks, and this is still not enough for some people who simply cannot be persuaded to leave that world. That's pretty potent, isnt it?

Aside from just 'looking different', the awareness and beliefs in these realms are fundamentally different from our world, in that they're worlds full of 'magical' unknowns.
For example, in Mr. Potters adventure there's a moment where you see the snitch before it's turned on. Its a metallic looking ball with "wings" that essentially look like bits of wire. How can wire flex so rapidly? Let alone make a metal ball fly? Your simple answer is.. you're now in a world where that just happens, you can't explain how, so don't even try. Mythical creatures do lurk in the forest, people do turn into animals and tiny stones do hold legendary power. There's no explanation, other than the fact you don't know enough about this world to argue with it. The viewer is now in a world that is very powerful, and they are very innocent.
This kind of gives a sense of exciting freedom. There are no 'laws' dictating what is and isn't possible. Anything could happen tomorrow. It also gives a sense of hope. Any problem could, potentially, be solved. How can you assume that there is no one watching, and nothing out there?
It seems to me the majority of these worlds are inspired at least partially by the Age of Faith, or pre-Age-of-Reason times, when ignorance left holes that were lovingly filled by religious and superstitious beliefs. This was a time when living creatures were born from rocks (or in the case of mice "a piece of soiled cloth plus wheat for 21 days", people's personalities were defined by excess bodily fluids, creatures the size of small islands await submerged out at sea, and spirituality overrode science as a reason for doing anything. People had no choice but to believe what they heard, and no doubt they saw the world as an imaginative, scary and limitless one.
Ironically, in modern life, by shunning ignorance and pursuing knowledge we actually have become capable of more, yet we feel more limited. By knowing all about physical laws, we're constantly aware of what can't happen. Experts are keen to remind us that telekinesis isn't real, there's no cure for cancer, and essentially all the land on the planet is mapped. We know virtually all the creatures and have categorised them several times over already. Mysterious, supernatural phenomena are always met as soon as possible with some boring rational explanation- and if not then we are informed they couldn't have actually happened at all. If you like the unknown, you may find that more depressing.
Having said all this.. We are no doubt on the innocent side of many paradigm shifts yet to come. Today's unknown is in the future, probably the sub-atomic, and space. In the future, there may or may not be spaceships.. we don't know.. If there are, we'll probably think it no more spectacular than today's cars. Right now, spacecraft are full of wondrous, innocent speculation, but when they are made, they will operate within known physical law like everything else, and overlooked as mundane tools by their generation.
Anyway i had no plan for where this was gonna go, so i guess ill stop there with that point. Ignorance is exciting bliss, and knowledge is predictable power. And humans will just have to fantasise about one or the other.