The retarded Slytherin plots continue to work...it really is insulting to the intelligence of everyone else that this continues to happen.
Harry's brotherhood friends are getting lazy and continue to be outmanuevered by the biggest idiots in the brotherhood.
I'm not holding my breath that they'll just start killing Slytherins to spare everyone else the danger.
Be fair. It seems well-established in canon that magic rots your logic and common sense to some degree (even Hermione was severely affected in books 6 & 7). Give the 3,000-6,000 year old guys a chance!