I guess it is just hard for people who have grown up with these books and have had a long time to form their view of the universe (unlike HP where the movies came out in pace with the books)
Well, they've had longer, but there was still a significant gap between the first Harry Potter book being published and the first film being released. (Philosopher's Stone
came out in 1997 in the UK, and the film adaptation was released in 2001. Between those years, Chamber of Secrets
, Prisoner of Azkaban
and Goblet of Fire
were published. I for one had a very clear image in my head of what the books' setting and characters looked like, but this was completely pushed out by the films.)
However, I do think your basic point still stands. I basically grew up with these books. I read the first two when I was 10, and the final five were published during the years that spanned my time in highschool. My friends and I discussed them as avidly as we discussed Harry Potter, speculating about who would die, who would end up together and where the series was heading. I should also add that it was only Harry Potter and the Tomorrow series that we ALL discussed in this way; they are the only two series that 'stopped a nation' (at least the teenage proportion of it) so completely. So I feel a sense of ownership of the books. They were there for me as I was growing up, they were something that united all of my friends, so that our experience of them was both collective and personal. Seeing a film version of books that were such a strong part of your life destroys the collective and personal experience, in my opinion. When you see someone else's vision of the books, you lose your own vision, and you lose the sense of the books as a part of the collective identity of your generation. That probably sounds a little pompous, but that's been my experience, and for this reason I'll probably not watch the film adaptation. The Tomorrow series is in no way one of my favourite series, but it's one that meant a lot, and I don't want it to stop meaning a lot to me.