I disagree.

Recently I've read a book, it was alright. I went on to the next book in the series, only to realise the main characters were behaving in a stupid manner very out of character, not reaching into some pretty obvious conclusions, and that the plot was being stretched for no good reason.

This annoyed me so much I put the book down and didn't finish. I don't consider the changes in the second book a consequence of better writing at all.