The problem with characters being allowed to post even short messages while wounded is that it removes one of the primary
disadvantages of being wounded: Not being able to communicate. Thus removing one of the major
advantages of a successful assassination of key nobles. A careful player could easily craft an order, or the sending of a key piece of information (like the identity of their attacker), in a mere 20 or 30 characters.
Being allowed to read messages while wounded is kind of an OOC nod to the players and the "don't make the game suck" guideline. But I don't see any particular reason to allow people to send messages, too. We already here lots of complaints from people that wounded characters can recover enough to read and send messages too quickly. The fact that we're hearing lots of complaints from both sides kind of leads me to believe that we have the balance just about right.