I totally agree that success rates are far from the only consideration here.
That said this discussion is very important because many people see things in terms of an overall tradeoff -- between security and privacy; or the amount to invest in different kinds of security. No matter whether we think of it that way, many others do. So it matters a lot if all the government's own examples of "success" are not in fact significant successes.
Also, with the current oversight mechanisms many of the government's statements come down to "trust us". When they are seen to be spinning something like this so blatantly, it erodes trust on anything else.
also important because 'foiling terror plots' may well not be the focus of these programs. demonstrating lack of efficacy on the stated objectives could help expose a wider agenda.
That said this discussion is very important because many people see things in terms of an overall tradeoff -- between security and privacy; or the amount to invest in different kinds of security. No matter whether we think of it that way, many others do. So it matters a lot if all the government's own examples of "success" are not in fact significant successes.
Also, with the current oversight mechanisms many of the government's statements come down to "trust us". When they are seen to be spinning something like this so blatantly, it erodes trust on anything else.