Really? I think with all the events and questlines AQ was done right and one of the best parts of Vanilla. It was very exclusive and Silithus wasn't really one of the popular endgame zones but everything leading to the opening of AQ was amazing.
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Y'Sharaaj is the only really dead Old God as he was killed by a Titan. So you're right. All the other Old Gods (except N'zoth) were defeated but not killed.