It might not be necessary, but it could save a bit of headache if we realize that we've messed a puzzle up badly and it'd take more time to get it correct from where it is than it would to reset. Barring that, even just an undo key would be super useful. That said, it's not a big deal.
Is "that's not big enough" meant to be another puzzle hint for the guy stuck on the island? Does that room contain a second puzzle?