Oh, you're totally right!!!! She *did* totally lose control of her characters after Book 4! So many unnecessary plot (if you want to call it plot) issues. Remus and Tonks?? Are you kidding me? And was it really necessary to have so many complicated subplots that did nothing for the narrative??
Sigh.
I suppose I'd have more standing on this point if I were also a billionaire author with seven books under my belt. ; )