Are abridged books acceptable?

We are just easing into TJEd and I am wondering what the thought is on reading the abridged classics to the kids. We read an abridged version of The Wizard of Oz and my 8yo is now wanting to read the unabridged so he can compare/contrast.

I've heard differing views on whether or not to "dumb down" (not my words) the classics for kids but am not sure what the thought is according to TJEd.. does that make sense? :)