Classic raiding was exhausting, yes. But in TBC it became great due to the reduced amount of players you needed for a raid.
Actually, you never ever could experience more and better raid content than in TBC:
Karazhan -> Gruul -> Maghteridon --> SSC --> TK --> ZA --> MH --> BT --> Sunwell
Karazhan was even great in 2.4, the last TBC patch. Who the f*ck would go to Highmaul in 7.2 or even in 7.1, after BRF was released? Nobody. Who was doing MSV, HoF or TOF after SoO came out? Nobody. With the recent raid design Blizzard is destroying all work they put in earlier tiers when they're releasing a new one.