Hmm, yeah, well that is a point I have had a problem with regarding the films. I have thought about it several times and every time I come to the same conclusion. Kloves could have kept the lines the same as they had been in the books but by the time the big line-swapping occurred Ron was already put into the "slow funny guy friend of main character" slot and he figured it wouldn't have worked in the films. Ron is some of the things from the films but he is also what you have mentioned in your question...making him quite complex, possibly too complex for the films. What really bites is Rupert should be able to reinvent the character Ron in the films, but he's not really been given the chance to do that. I think with a new screenwriter for Film 5 (and if Rupert is still there) he might be able to be given the chance to redeem the character a bit. Time will tell. But to give Kloves credit, I think movie viewers who haven't read the books really enjoy Ron and his role, even though they're being given an incomplete version.

I think Grace is wright, alot of Ron's sentences are said by Hermione in the movie. In the books Ron is a bit goofy, but the books do show that Ron has some knowledge of the wizarding world. In the movie Ron is potrayed as the goofy best friend, who is there just to be funny. Only in the first film did Rupert get to play a brave Ron