Here's the difference it makes:
The motives behind the attacks factor into our foreign policy and response in that region. Congress wanting to know if the State department (run by Mrs. Clinton) is competent enough to recognize who was responsible and if she took appropriate action very much makes a difference.
To those who claim that the right is exploiting this for political gain, I ask the following:
If the White House and the State Dept. knew Al Queda was involved from the beginning, then what was the month-long narrative about a movie-induced riot if not politically motivated?
The welfare of humanity is always the alibi of tyrants