New Editions and Old Fans

The announcement of the upcoming 6th Edition of the Hero System got me to thinking about the process that goes into conceiving and producing a new edition of a game system (especially a well-established and popular one).  From reading the Discussion Forums about the new edition of Hero, it looks like there is a fair amount of dialog about exactly what to change and how extensive those changes should be.  It's very interesting stuff to read.

Many games that were recently updated, including the 4th Editions of Shadowrun and Dungeons & Dragons, made significant changes from previous editions.  The 5th Edition of HackMaster also looks like it will be a pretty big departure from the previous edition (some of that by necessity I understand).  I know the case of D&D is a fairly unique one, but I wonder how dangerous it is for the average game company to make such a radical change in an established game.  How many new players are gained versus how many old fans are driven away?  Can the new edition of a game sink an established property?

Also, it looks like many new editions are produced in order to 'streamline' and 'clean up' an older edition.  Is this what the average RPG player wants?  I ask because, although I have been a fan of Champions and the Hero System since the early '80's, I have to admit that I wouldn't mind a version that requires a little less calculator work.  But is this what most Hero fans want?  Enquiring minds want to know....