The reason I favor compartmentalizing flags is that if you give people too much power beyond what they need to do a simple assigned job--like say managing the Image Gallery or overseeing the message board, they are more likely to get into trouble and mess up things they shouldn't be messing with at all. 

Now this may not be true with your forum, but I run two busy, all-around type forums with all areas active, and having assistants to focus on a specific task without having their own magic wand to undo a hopefully carefully set up and managed forum seems like common sense.