It's not a matter of being careful...it's a matter of following rules developed to ensure the safety of you and others. See Royal Caribbean Guest Conduct Policy, page 3, under "Prohibited Items." It's not just about irons.
People can find all kinds of reasons why irons shouldn't be on the forbidden list. Let's face it, it only takes that one forgetful individual that leaves their iron on while sitting on something that can start a fire. What I can't comprehend, is how they allow people to smoke on their on their balconies, especially after the Star Princess fire in March of 06.
One of the many great aspects of cruise-chat is that members are happy to answer any questions that arise. The topic of irons is an important safety issue, and it doesn't bother me that it's been asked before...or that it will come up again.