...More so with the upcoming Level Squish, which makes the need more obvious. I'm talking about the Timeline continuity.
Like it or not, Blizzard's gonna need to get into the habit of updating older content to reflect the passage of time every expansion or every other expansion and more so for new players. Post-Cata, Blizzard should've REALLY done it after MoP, Legion and now BFA. Zones and Expansion Areas really need to be updated to reflect more recent events:
- Silithus: Sargeras' Sword is in the middle of it. 'Nuff said.
- Darkshore War Front: The war for Lordaniel devastated the region. The Night Elves seek to restore the land while the Horde works to withdraw the remnants of their forces through Ashenvale to The Barrens.
- Ashenvale: The Night Elves work with the Worgen, Draenei and other allies rebuild their devasted outposts. Meanwhile, the Horde continues to move their forces from Darshore through Ashenvale to The Barrens before their supply lines are compromised.
- The Broken Isles: All zones updated to reflect the events of Legion and BFA.
- Kul Tiras and Zandalar: All Zones updated to reflect the events of BFA.
- Pandaria: All zones updated to reflect the events of MoP, Legion and BFA.
- Draenor: All zones updated to reflect the events of WoD and BFA.
- Northrend: All zones updated to reflect the events of WotLK, Legion and Shadowlands.
- Outland: All zones updated to reflect the events of TBC, WotLK, Cataclysm and BFA.
- Cataclysm Areas: Updated to relfect the events Cataclysm and Legion.
...Those are just a few examples obviously.
Allied Races' starting experiences would also be merged with existing races' which would also be updated:
- Elynn Forest: Human, Kul Tiran Human, Tushui Pandaren and Void Elf. The recent wars against the Horde, N'Zoth and the Legion have devastated Stormwind and the surrounding region. Anduin decides to put some effort into rebuilding and securing long forgotten regions--Westfall, Duskwood and Redridge--some of which have been overrun while attention was focused elsewhere.
- Durotar/Echo Isles: Orc, Mag'har Orc, Goblin, Darkspear Troll and Zandalari Troll: Years of fighting wars of distance battlefields have left Durotar in a state of disrepair. Thrall and Eitrigg call on their allies to assist them in giving key outposts in the region a much needed upgrade.
- Dun Morogh: Dwarf, Dark Iron Dwarf, Gnome, Mechagnome: The arrival of the Mechagnomes to the region allowed the Gnomes to further the efforts to reclaim more of their fallen city of Gnomeregan. The stage is set for the city to be reclaimed once an for all. Meanwhile, Muradin Bronzebeard agrees to Moira's request to build an access roads to the Burning Steppes, proving overland routes for the Dark Iron Dwarves to Ironforge.
- Mulgore: Tauren, Highmountain Tauren, Huojun Pandaren and Vulpera: Baine invites the Highmountain brethren as well as the Vulpera to Mulgore for a cultural exchange as well as to strengthen the bonds of their people. Ji Firepaw relocates to Mulgore as well to change things up.
- Darkshore/Ashenvale: Night Elf. The Night Elve were devastated by the destruction of Teldrassil but not they are far from defeated. They work to rebuild their shattered settlemants on Northern Kalimdor.
- Tirisfal Glades: Undead. Abandoned by Sylvanas Windrunner and The Undercity lost, The Forsaken struggle to find a new identity and a new purpose for themselves within the Horde. The pain is deep but they are resolved to endure.
- Azuremyst/Bloodmyst Isle: Draenei and Lightforged Draenei: The Draenei and their Lightforged brethren come together to further develop Azuremyst Isle and Bloodmyst Isle so that the can better assist the Alliance forces across Azeroth.
- Eversong Woods/Ghostlands: Blood Elf and Nightborne. The Blood Elves accept aid from Suramar in restoring much of the damage still left over from The Third War and The Scourge Invasion. The presence of Alleria Windrunner in The Ghostlands could mean new conflict or a chance at reconciliation.
- Gilneas: Worgen. Genn Greymane leads his people back to their homeland for the sole purpose of reclaiming it. Even though The Undercity is destroyed, there is much work to be done to reclaim Gilneas.
...My head canon's in overdrive obviously.
Anywho, the timeline and continuity is easy to fix with some effort. You could even just have an NPC in every starting zone saying "Much has changed since The Cataclysm. Before you can experience the current story, you must become stronger than you currently are. As you travel the world you will learn of past events that shaped history up to now." Simple, requires little effort.
Same with expansion content:
- Outland: The opening of the Dark Portal allowed the Orcs to return to their shattered homeworld and for the Alliance to reconnect with long lost allies.
- Northrend: The Alliance and the Horde worked with the Argent Crusade and the Knights of the Ebon Blade to defend the world from The Lich King and the Scourge.
- Cataclysm Areas: The emergence of Deathwing changed the world. New and Old allies emerged to join the fight for our world.
- Pandaria: The lost continent of Pandaria was revealed by The Cataclysm for the first time in centuries. It was far from prepared for the war brought to its shores by the Alliance and the Horde.
- Draenor: Past meets present as Heroes journey to an ancient version of Draenor before it became Outland.
- Broken Isles: The Fourth War devastated Azeroth. See how the world's Champions snatched victory from the jaws of defeat.
- Kul Tiras and Zandalar: New allies join the Alliance and the Horde fight for dominance. Little did both sides realize, there was another force working behind the scenes against both of them.
...Context would help quite a bit in short. You can simply explain to folks They're going through older content first so that the can learn of events that brought the story to where it is now. Not hard to add and it won't be breaking the fourth wall either.