Hero Units have been in every single Blizzard RTS game.
So I guess you gotta switch to Counter-Strike... Opps, you can't, they have Tanya. Which is also a hero unit in single player.
Can't play Age of Empires either, Hero Units in single player also.
Perhaps you should just give up on all RTS games, seeing how they all have Hero Units, which is a mistake.
Unless you refering to the leveling up abilities of the Hero Unti, which isn't a mistake but one of the best fucking ideas ever.
If you ever play the offical downloadable Campaigns, you will see how badass it can get, and give you a taste of what WoW will be like. Raxor is ultimate coolboy omega.