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.
I disagree. A messaging system should not be in the core part of a decentralized currency.
We have
so many ways of sending simple text messages to each other. Why on earth would we want to put this sort of trivial data in the block chain, to be stored for ever and ever?
Every single bitcoin transaction is
necessary for the system to work; we need them to figure out if an output has been spent.
Messages like "
A no. 5 with extra cheese and mushrooms" is the exact opposite: absolutely irrelevant to the currency itself, and utterly unimportant as soon as the good that the payment was for has been delivered and consumed. Storing this message for eternity in the block chain would be a waste of the scarcest resource in the Bitcoin system: storage space.
It helps prove intended use of the money (similar to check memo), which might be helpful in law. If the intent is disagreed with, money can be refunded with the memo stating so.