A better system I think, would be one without rank. There wouldn't be Hylian Nobles or Knights or any other non-functional rank or role. Functional roles (e.g. Administrators, Moderators, etc...) would remain anonymous (i.e. No badge or different color username), which might eliminate elitism if there is any, and would probably improve security in the sense that if a cracker wanted to break into the site and cause problems, they wouldn't know who's account to break into. If a person needed to contact moderator, they could do so with a textbox that sends a message to all of moderators (sort of like the Report Post function); The same could be done with other functional roles. Reply's as a moderator would also be anonymous (e.g. Subject line could read: Mod#41 has responded to your inquiry)
As far as motivation; this should be mostly intrinsic. You make good posts because you want to provide others with the best information that you can give them, as well as improving your own skills. Writing good posts because you want a purple username, and a badge (as well as access to special sub-forums and some chatbox functions), seems like a rather empty fulfillment. In other words, what exactly are you gaining from your HK rank that's so damn important?