So, basically, for the past quarter century.
Your reminiscence of past MMOs may be fond, but I remember the frustration of spending two days trying to figure out where to swim to reach the half-an-amulet necessary for Druid water-form. Folks didn't read quest text back then either.
Dropping the slot car race track design of instances wouldn't result in better, more interesting instances. For an example, I refer you to the circa 2008 version of the Mauradon dungeon, including the map. It results in a long journey, frought with an almost guaranteed 30 minutes of getting lost/having to backtrack, or abandon the instance after an hour. Or the new-and-improved slot car race track design of Mauradon.
