Transaction of very small amount require higher transaction fee by the bitcoin network (this is embedded within the bitcoin client code).
I have set the price to avoid the "too low transaction" punishment, to cover the current transaction fees and to leave a small margin that supposed to cover the running costs of the service.
Currently I am very far from covering the costs, but if there is a reasonable demand I could reduce the fee.
This would require an update to btcmsg html/css/javascript client and setting the new values in the server side (few seconds work ...), but considering the deep dive of the BTC/USD rate took, I don't see the price so high now.

What will happen to messages once a newer client version is published?
The old messages will be always visible by the old clients as well as new clients.
New ascii messages will be always visible by old clients as well as new clients.
Non ascii messages as well as any other new feature may be only available using a newer client.