Vanuslux
Explorer
Minor note, the EULA associated with DDI does say it is for one person only (or two people if its with an adult and minor child above the age of 13). Of course, this could be something that WotC is looking the other way at for the moment.
EULA is not enforceable; historically, EULA have never held weight in court. Plus, I don't honestly think that WotC is going to pursue something as silly as this.
They likely turn a blind eye towards it, as they have no way to track who's using it (beyond the logged IPs where the game has been installed across five computers per update).
So basically right and wrong comes down to what you can get away with and what you'll get punished for?