i am currently trying to clear The floodplain of Mahnkelon in Nightfalls for the Vanquisher title. Upon exiting Moddok Crevice and clearing the main area then going to the East you encounter a group. In this group is a Steelfang that has the BOSS aura yet it is not named...
wreaks havoc for my hero/hench group...havent made it pass yet
The unnamed "mini-bosses" have been in Tyria from the start, they give nice variety to the otherwise monotonous mobs. Haven't met any in other continents so far though...
I think they've added bosses to Hard Mode in order to change things up and give a boss for lb and ss bounty point bonuses (in Nightfall) and also give a possibility for elite tome drops. They didn't bother to add greens to them though or names in some cases.
Griffons mouth has always had 2 unnamed Snow Ettin bosses (monk and warrior). My guildies always assumed that those bosses were too poor/stupid to acquire names, especially since the monk boss doesn't have any skills either.