They have to please the shareholders. Thats probably the main reason they dont want hb available to the customers. Obviously, if psp users can download free games, they will spend less on the commercial games. So, less dividends for the greedy shareholders.
I have found in the past, that sony reply personallay to a good hand written letter. I sent one to scee in dublin and got a reply within the week. Although, this was to do with my ps2 breaking down...you know, when it stops reading your games.