The Wormhole wrote:

Fun fact: The original plan was to have Vulcan conquered but it was felt that Vulcan was too prominent a planet to be lost off screen with just a line of dialogue mentioning it. Betazed was chosen since it being Deanna Troi's home would give it resonance to fans but was obscure enough to get away with an off screnn loss.
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A similar idea was thrown around about Spock dying (during TNG and DS9), but it was decided that such an universally popular character was too important to kill off-screen.