They were bigger, had more of a story, more varied encounters, generally weren't so linear.
Compare anything with BRD for instance. That instance is ENORMOUS, has masses of different encounters and is dripping from pretty much everywhere with lore and character. It would easily be raid content if they made something of that scale again.
And yeah, running across WPL/EPL and crossing the border into Silverpine on the way up there trying to dodge horde. Was amazing