I believe that Bitcoin should follow its initial design goals, and should not try being everyone's everything (chat client, name resolver, distributed evernote, torrent seeder... )
Absolutely, but limited encrypted messaging attached to a transaction looks like a core feature of a payment system. Traditional payment systems also have this feature.
And there you have it.
It is NOT a core feature of a currency, in fact although some jurisdictions might not currently prosecute people for writing messages on e.g. dollar bills, I believe there was a time and/or are or have been jurisdictions where "defacing a coin of the realm" was not only offensive but "an offense".
Bitcoin is a currency. Stand by for a payment system, "coming soon". (4 to 6 weeks or so?
)-MarkM-