The most important thing to note here is that if Snowden can bypass the logs to cover his tracks then so can many of the capable people in the NSA that may want

The most important thing to note here is that if Snowden can bypass the logs to cover his tracks then so can many of the capable people in the NSA that may want to use those systems for nefarious acts. A low level analyst using the system as intended probably won't be committing any serious crimes they can get away with, but there are probably many people in the NSA smart enough to use these systems for wrongdoing in a way that effectively covers their tracks. Compliance departments are a tricky thing. Anyone who has worked in the compliance area is pretty much fully equipped to evade compliance. Just ask the Societe Generale Group.