I never really understood why some players consider exclusive content a negative thing for this game. Lets be frank about what exclusive means. This means content that required a certain dedication to the game, and time commitment. Being able to play well and organize with other players to accomplish legendary feats.
Skip all the talk about TBC and Vanilla being the "least accessible content blizzard created," lets talk about the here and now.
1) Having exclusive mounts and cosmetic items that disappear after the end of an expansion. Why is this bad? Should rewards not be tied to the context of the content they relate to? In other words, if cosmetic and vanity items are rewarded to players who do extremely difficult things like heroic raid bosses, or gladiator PvP, why shouldn't they be removed from the game when new expansions trivialize the content?
2) Raiding with only 1 mode of difficulty, and 1 form of raid. Yes im looking at you TBC. Why is it a bad thing to have this content aimed towards players who are on a higher echelon of playing or commitment? Even though only "1%" (insert any other low percentage from thin air here) of the player base raided, the game substantially grew in subscriptions. What was keeping people subscribing, when they "never got to see end game"?
And please, dont give me "the flair and excitement of a new game" or "the game was new back then" The game is new to anyone who picks it up for the first time even now days.
The game is here for you (us) the players to have fun. Now if all you consider fun is "raiding" in whatever difficulty you "raid" in, then perhaps the game would lose your subscription. This is not however the case with World of Warcraft at all. In fact, even though more characters (not players) have seen "end game" content, it is still a minuscule number of people "raiding" compared to the population of WoW. I guess though since blizzard has trained players to think that all end game consists of is raiding, the problem lies in their own court. The real question you have to ask yourself.. what did end game consist of for all those players in Vanilla, TBC, and early WoTLK if only "1%" of them raided?