As AdWords accounts age and accumulate keywords, it's easy for mistakes to slip in. Occasionally, negative keywords accidentally block all of the search terms of certain keywords -- this creates "dead keywords" that don't get any impressions and crowd up your account.
This improvement will scan AdWords for any keywords that are completely blocked by a negative, and will give you the opportunity to either remove the offending negative (if it was added by mistake) or to pause the blocked keywords (if the negative is warranted and the keywords are no longer relevant).
That way, you'll either unblock the traffic or clean up your account. Regardless, you'll be left with a tighter account structure, which is always a win!