So, let me understand this.
A user goes to CryptoGraffiti and writes whatever message in the space given. Then, your software generates bitcoin addresses in relation to the human text/message a user just entered. After that, I use my wallet to send bitcoins to those addresses your software generated? However, the "messages" now in the blockchain aren't in plain text. You need to use your software to convert it to plain text? Do I have this right?
If you open a block chain file in a text editor that displays ASCII characters, then your messages will be there at the first glance. You are directly writing the byte values of your message to the block chain as they are indicated by the ASCII table. If anyone displays the block chain bytes in ASCII table encoding, they would see your text, surrounded by a lot of gibberish. In essence, the same way this famous sentence is stored in the block chain:
"The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"