These players are missing out on a valuable tool that contributes positively to the intrigue and social aspects of SD. They have no idea that this option even -exists-, and if they did get a notification about it, it was probably within the first week of their time in Withmore when new immies are bombarded with plenty of other @options and requirements to focus on.
This leads me to my proposal – that encrypted SIC messages be turned on by default, and if people don't like having that info on their screen, they can turn it off manually in @options. In a game where data is everything, and where keys can convey invaluable information about alliances, friendships and loyalties, it makes no sense for this freedata flow to be turned off just because the encryptions might look confusing to immies at first sight.