Posted March 14, 2019
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I think the lack of rerelease of the expansion is more due to Blizzard not wanting to bring it back into canon. They've shown a reluctance to canonize expansions not developed by them directly, as seen with Starcraft Insurrection and Retribution, or Warcraft 2's 4 authorized expansions other than Beyond the Dark Portal.
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Sierra might have just been the publisher/distributor of the game;another studio actually designed the game and the rights eventually reverted to them and were not included when Activison acquired Sierra.
Also, regarding your following post, I didn't have any trouble installing the expansion on a 64 bit system.