The act system is how the game prevents you from progressing too far with the incorrect assumption that rot13(gurer vf bayl bar svyr cre gvzr-pbqr). [EDIT: it only slows you down, my bad!] If you make that assumption and don't read 06-ST closely, you'll never find the file that tells you about the act command.
The real problem, in my opinion, is that the agent implies that 07-ED contains nothing of value; that comment should encourage the player to look at it.
Also, I could not disagree more with your final paragraph. The two most rewarding files (you know the ones) can only be solved after figuring out the mystery. The agent's final note may not be much of explanation about the curse, but surely the fact that rot13(gur ntrag vf gur svany crefba va gur punva) counts as a resolution to the story.