Here are some examples of other characters from World of Warcraft who fall under the category of "rogue". You might recognize them as ruthless tacticians who employ subterfuge to accomplish their goals, noble or otherwise, and to protect the things that matter to them.
Putting on my tinfoil hat, I think the reason was so they could stick an Arthas look-alike in the marketing materials. They probably started with "remember that iconic blond guy with a spiky headpiece and a cool mourneblade from Wrath?" and worked backwards from there.