Player security settings is a fairly hotly debated topic. On one hand, adding settings like this is yet another layer of abstraction, which adds complication to the application ( Everyone will have to drill into the menus or settings, and ensure that it's set the way they personally want it ).
 
 On the other hand, it seems like there's a lot of people who would rather just "take the pens away" as it were, instead of possibly butting heads with their players.
 
 It's something that's on the radar, and is being considered. However, for at least the duration of the beta, the dev team has decided to leave it open, and concentrate their time on adding and refining features and squashing bugs, rather than locking things down.
 
 It may be revisited down the road, but in the meantime, I'd suggest telling your players that those doodles look suspiciously like Gelatinous Cubes.
 
 Have you ever fought a 40 foot tall gelatinous cube shaped like a phallus?  They fight DIRTY