Re: Although I agree the NSA have not really provided a blazing list of sucesses
If capability and accountability are so much at odds that there is absolutely no way to have one without hurting the other, then a balance will have to be struck, and capability will just have to suffer a bit.
Unaccountable agencies are intrinsically harmful to democracy, and that harm cannot be ignored altogether.
Providing sufficient information to guarantee accountability might hurt capability a bit, but I really do not believe that it will cripple it.