Tobold made a great point about the gaps in the random dungeon system.
If you level using the LFD tool, then you’ll see most of the available instances from vanilla WoW. However, when you get near a level cap from a previous version of the game, rather than putting you in the (formerly) high-end dungeons, the game skips forward to early dungeons from the next expansion. So, when you get to level 58-59, instead of getting into Scholomance you’ll wind up in Hellfire Ramparts. At level 70 instead of getting into The Botanica or Shattered Halls you’ll be placed into Utgarde Keep.
Since I leveled a character from the mid-20s through 80 exclusively with the LFD, I can attest to the gaps in the dungeon experience. Here’s a list of instances that I was never placed in while leveling:
- Caverns of Time: Durnholde Keep
- Shadow Labyrinth
- Shattered Halls
- Caverns of Time: Black Morass
- The Mechanar
- The Botanica
- The Arcatraz
- Magister’s Terrace
Those are some iconic places in the history of WoW. Some, like Scholomance and Stratholme and the Caverns of Time instances, are full of lore. Others, like Shadow Labyrinth, are very memorable for their interesting fights.
Such a shame that new players will never see some of those great instances.