Originally Posted by
Aresk
The arakkoa in WoD were really interesting up until they opted to join the Legion. Similarly, the Klaxxi Paragons were a really interesting group to work with up until they threw their lot in with Garrosh for reasons. Lastly, the Zandalari in Cataclysm and MoP were villain batted hard after being perfectly reasonable allies in Classic.
Sylvanas was leader of a hostile power who invaded his homeland; I don't think shooting her was in any way a crime, particularly given everyone who is raised is supposed to be given a choice (at least up until BfA). His greatest crime was treason, over which he killed himself. But I do agree it would've been interesting to have him stick around a bit longer.