In my book Blizzard got the Achievement “Eternally Unforgiven” for Cataclysm, destroying those great old zones and quests. I have just levelled a char in Retail and also one in classic. Classic world and quests feels more “real” if I can use that word. Vanilla was a world that got more and more unforgiven and corrupted the longer from home you went. Later xpacs gave more of a “theme park” feeling. Not to mention the horrendous mobs scaling! No part of the world feels dangerous or scary now. How cool was it not being a night elf on the way to Ironforge… that scary travel through wetlands - it felt like an epic journey. And the great feeling when your char was stronger so that you could go back just beating those crocodiles for fun.
IMO getting rid of those epic quest arcs that took you all over the world was the biggest error.
The Scythe of Elune.
The Defias docket.
Linkins Sword.
Getting the key for Scholo.
And others. They gave a sense of a huge world unlike now where each zone is in it’s own isolated bubble.
Also there where some areas where you either needed to be very well geared or grouped up to go into, The Troll city in Hinterlands was one, full of elites that would one shot the unwary.
This is the thing that diminished over the years. World building, to the point that Blizzard finds any content outside an instance a theme park. Where your character scales to the gear you wear.
I would recomend you do touch classic it will give your feeling back.
Make a undead like me and take a walk to pyrewood village in silverpine forest.
A perfect town to start your adventure