The main reason is that in became unmanageable. Beyond all the racist threads and harassment that was a daily part of the boards, Howard was not happy with people sharing information such as (i) where to get mp3s of his radio show (ii) how people could d/l the uncensored E shows that he was charging a $4.95 rental fee for and (iii) when he cut his Sirius deal his contract provided a cut of revenues he generated, which were to be tracked by use of a signup code Howard provided, but people on the board found better codes and rebates and this means real money to Howard and his agent.