They didn't.
Things were new back then. Flying was new.
Flying didn't really start showing its teeth until late WotLK.
Flying in Northrend was locked behind a reasonably okay mechanic - Cold Weather flying - and you would get it reasonably fast (68).
Now everyone is used to flying or getting flying as soon as they reach max level, so when Blizzard changed that and gated flying behind content/rep/patches, the cravings began.