Forming groups and traveling to the dungeon entrance manually.
Using 1-handed swords on my rogue back during BC. I hated sub back then even though it was amazing, now I miss the old 1-handed sword sub. Everything is about daggers now for rogues .
Pallies were super useful for Hyjal trash too. I think they were capable of doing MTing everything except Illidan and his stupid Shears and were in many cases better due to the old CTC and being uncrushable.
Angels and AirwavesCHVRCHΞS - Lemaitre - Motion City Soundtrack - Bombay Bicycle Club - Los Campesinos - Empire of the Sun - HellogoodbyeLaethys - High Elf - Assassin - Marksman - Frostmourne - Orc - Rogue - Sea of Sorrows - Norn - Thief - Aldmeri Dominion - High Elf - RogueThaumaturge - Borderlands 2 - Mechromancer - Battlefield 4 - Engineer
Of the comments given, a common one is using ground mounts and really having to travel around the world the hard and long way. But this is one thing that you still have the option of. You say you miss it, but do you ever just run around on your ground mount for shits and giggles while questing outside of areas like the Isle of Thunder? Probably not; you'll use your flying mount any chance you get.
I like to reminisce about the way the game used to be, but in the end I'm okay with the changes (for the most part).