Most classes have cutter specs but there are others that people never tried long term the problem was sometimes Naxxramas gear made things possible. Look at Hemo Rogues for example, Fury tanking? Thats new to me there is also Shockadins, Smite priest, Wrath Druid? Who wants to get Naxx gear to try something and the knowledge only existed in private servers as well by the time Naxx came everyone i knew was resting for the burning crusade expansion which imo i am glad about this time the time between expansions was too short and you need long term investment to pull of a weird spec.
Some of those cookie specs are only possible because of end game gearing, others because of private server values, and all still sub optimal compared to focused specs. Naxx was out for quite a long time before TBC, with most of the bosses on far so it was only really 4horse, Sapphiron, and KT loot that was missing. I must say though I am looking forward to it this time around just as much as the first time around.