Warld of War.net has posted a link to this really interesting forum thread. It's about why Blizzard won't change the server rules. Here's a snippet:
At the heart of it, we have two core mechanic rulesets for realms: PvE and PvP. RP realms are additional behavioral rulesets, but they have no changes to core mechanics.
Every other ruleset that has been proposed asks for changes to core mechanics. The designers are very much dedicated to the faction vs. faction idea, first and foremost, thus leaving FFA and co-op potential rulesets in a poor light before consideration even begins... but it's more than that. When you add more rulesets that change core mechanics, you then have to account for these mechanics in every single change you make to the game moving forward. This adds exponential degrees of complexity to each and every addition to the game, and increases the likelihood that something, somewhere, won't work.
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