I think you're being too critical, especially if you are trying to compare them to the LOTR trilogy.
These book are on average less than 200 pages each. How involved did you expect them to be? And how could you expect that they would contain the same level of detail as the LOTR books, which are all at least 4-600 pages long?
At least you did read them, and your opinion is based on some actual knowledge of the stories. And since you didn't much care for the stories, I can't really expect you to enjoy the movie. I'm glad your kids liked it.
I don't, and I didn't. I just thought it was a very thin story. The main plot of getting the White Witch, and the subplot of Edmund. And both about as linear as you can get. With all the subtlety of a bottle of Tabasco.
I'm not saying that either the movies or books are objectively "bad". They're not. They tell the story the way Lewis wanted to tell it, aimed primarily at kids. I'm just saying that I personally found the story to be thin.
There were some things about the movie I liked, so its not like I didn't "get" it. It was enjoyable. It's just that, like Chinese food, it didn't stick to the ribs after it was over, maybe because the tone was just too fantasy-oriented for me. Not that I dislike fantasy, but that there wasn't a sense of...reality to this particular fantasy. But I did like the scene with Aslan being dragged to the alter. It was the one scene that -- to me -- had some grit and realism to him. And it helped draw more strongly the parallel with Jesus.