I think it is not a question of liking or disliking. Even when I dislike a classic I have to accept that it is a classic and therefore will have to read it, just for the sake of my education. LotR is one of those books, which you have to read, like the books of Shakespeare, Jane Austen, Wilde, Goethe, Schiller, Victor Hugo, Friedrich Dürrenmatt, Gottfried Keller etc. etc. I also don't like some books those people have written (Victor Hugo is just to depressing) but they are works of literature and in order to educate myself I'll read them.
And to think that imagination is childish: Were all the people who told stories, ballades and sagas in earlier times childish? Stories were a part of every culture and a very important one. What do you call the "Nibelungenlied" then? Isn't this also a piece of literature? But it is full of imaginary beings like dragons and dwarves (called Nibelungen there). Or what is with all the Greek legends and the Saga of Gilgamesch? All these stories were teachings, they told the listeners something about the world. And that is still the purpose of stories and LotR also is in this tradition.
I think someone who doesn't use his imagination is a very poor person and misses one of the most important aspects of life. Where would we be without people who use their imagination? Would we be so advanced as we are now? If everyone would think that way your mother does, SimVig, we still would live in the stone age!!! Visionary people are taking the first step into the future and the rest of the people, who are mostly too dull and too stupid to make this first step, will follow sooner or later, even when they first say "This is against tradition!" or "This is childish, no adult person should think about such things!". Sorry, I just hate people like that. I think such people are the more childish ones, because they try to force themselves into something (to be adult). What they don't understand that to be an adult means that you develope your mind and learn to use it and not to act in a certain way. When you achieved to use your mind on a certain level (of course this level depends on your abilities), then you are an adult. So therefore any person not using or training it's mind is not adult, even when he or she is has reached the age of adultness. And with this in mind I must say that I have seen young people who are more adult than some people who claim to be adult. In the Renaissance they said "Humans aren't born, they are educated". Even when this sounds harsh and brutal (every child would be not a human), it has some truth in it. I would just rephrase it into "You aren't adult when you reach a certain age and learn to act in a certain way, you are adult when you learn to use your abilities in a proper way". That is the difference between a child and an adult person.
Don't bother my talking and let's get back to the topic

I just really hate it to see such people who act like they are adults but in fact are just big children who like to play a little "I am an adult person". Sadly, a lot of people are like this today. So you guys just buy every book and read it, may it be fantasy, sciencefiction or whatever. It came never harm from reading a book (wasn't this sentence in "The Mumy"?), you can only learn from doing this. Worst thing that can happen is that you learn how bad someone can write a story and take an example of it (and never write a story as bad as the story you just read).
By the way, I read the books years before the films. I learned about the film about in 2000 or so and was really excited to see my favorite book on the screen. I probably read it every half a year. And of course also the Silmarillion. And of course the Book of Lost Tales. But at the moment I have some problems with money and I can't buy more