It's the same as one of the puzzles in Myst (original), specifically, to power-up the spaceship.
You have to gauge carefully simplicity and reward. I'm guessing the develop was afraid that too complex a puzzle risked making it hard to complete for some. The alternative is making it very simple, at the cost of such a potential problem.
One perfect example of this, look out the last puzzle sequence in PoP: The Forgotten Sands. You can solve the problem with a single move on your first visit, which is also meant to teach you how the puzzle works before it asks 'move' from you. If you do, chances are you can't complete the game because you didn't get the puzzle and it just grew much more complex.