I know you rose-tinted people dont want to hear this BUT: Raiding was MUCH mroe casual in TBC then it is today. People didnt min max in any deagree to what they do today. The best guilds cleared content and then sat there with nothing to do for a fuckload of time.
If you think making 1 difficulty instead of 4 free's up enough dev time to double the amount of bosses in raids then you are sorely mistaken.