Dude, they simply had less resources and less experience to fill up zones with mobs, quests and mechanics. In Cata game entered mature state, Classic->BC, BC->Wrath and Wrath->Cata were big sharp in quality, after that room to improvement was smaller.
You add some reason years later they were doing empty zones on purpose. I honestly don't understand what is "comfy" and "relaxing" about hiting autorun and ride through wasteland.
Sounds like (and it's not first time I got this impression) you just don't enjoy WoW anymore. That's fine. But you made Nostalgialand from Classic-Wrath era and try blame everything on current game. Honestly, I suggest to think twice before playing TBC/Wrath Classic, it's possible you won't find "comfort" and "relax", but boredom. Classic Vanilla already shattered nostalgia goggles for many people.