If it is made optional, and you decide to pass on the option, you are accused of breaking the "don't be a dick" rule, thus really not making it optional anymore but mandatory.
This was one of the worst Pathfinder mods I have ever played. We ended up only having one combat because we had no one able to climb the chains risking a huge fall so far up except for one character who once got blasted by the wizards knew he was outmatched and climbed back down before he became unconscious and fell. We didn't fall into the trap either so lost out on that gold as well. Very bad taste in my mouth.