So how many actual trouble players should you be worried about, as opposed to random bored players accidentally or unintentionally messing up things in your Dream? For all the time and effort that goes into a well designed public map, the number of malicious characters you're likely to encounter is small, usually never more than 1-3 at a time.
So why secure your Dream at all? Well, the satisfaction and lack of stress when your Dream takes care of a problem itself instead of costing you and your staff valuable attention is worth every line of DS it takes. You can use these principles of Dreamweaving and De-trolling to ensure a positive experience for every visitor to your Dream!