I think there was just too big a jump in difficulty coming from Wrath Heroics. Players were used to vastly overgearing dungeons, which they’d been doing for the better part of a year in Wrath.
But in 2024 when Cata Classic launches, this playerbase wouldn’t struggle nearly as much. Hopefully Blizz realizes there’s no need for their titanforged crap in Cata and just releases those dungeons as they were.