TBC, flight 1st comes to WoW, awesome everyone yells for ice cream the honeymoon begins.
Wrath, flight gets bonus speed and with book your alts get it sooner. Honeymoon continues and everyone still happy.
Cata, flight is open everywhere for the most part, nothing new is added to flight in progress. Players master all the ways to use it completely to their advantage to gather and even use it in classes to cheese gathering the quickest. Speed quest, avoid mobs, Camp rares, camp other players in PVP and dozens of other lame work arounds in the game that makes game play more lame in the long run. Holes are starting to show and the Honeymoon is about to end for TBC flight for many players.
MoP: TBC flight becomes stagnate, and loses much of its charm for a number of players, it just is there as just another tool to get the job done, no romance to it left and the Honeymoon feeling is really over with.
WoD: OMG where is my wings my pants danger Will Robinson, Blizzard un announced tries to remove flight for a flightless xpac. (Shame on them) ends up forced to change it back, but with Pathfinder being born) Bring forth the torches and pitch forks.
Legion - Shadowlands, Same thing Pathfinder with TBC flight stagnate, yet provided half way threw an xpac with the pathfinder achievement.
Dragonflight - New style of flying for WoW, Dragonriding given at the start after short questing. TBC unlocked by pathfinder half way threw xpac. Torches and Pitchforks still from all the I hate pathfinder people.
TWW announced with Pathfinder still active but achievable from the start with the least amount of requirements ever. Dragonriding renamed to Skyriding and TBC fight renamed to Steady Fight. Skyriding is active from the start. Torches and Pitchforks again from those who hate pathfinder or anything to do with change to flying.
Thus is the history of flight in WoW.