Indeed.
The other thing is that it impacts more people, especially the not-so-RP-inclined folks. Because the people who don't like to read long RP messages probably never will and just skip them. However, if you're always just keeping an "RP tone/attitude" in your regular letters, orders, etc then even those people will read and see them and perhaps it will encourage them to give it at least a little effort as well (using proper titles, etc.)
It is probably wrong that I am having this discussion while writing letter from my "buffoon" character who is currently lamenting the death of his good captain from a poisoned compass which was provided to him as a devious plot from our enemies. Thankfully he was recently informed that midget tossing is still a reliable way to navigate.