4-player dungeons still end up being a bit of a faceroll, but it's definitely possible to wipe on the 8-player bosses if mechanics are not observed
So while just scaling down characters is technically not hard to do and there's tech in WoW for that, it's never the same as playing previous expansion. And players want genuine experience.
And preserving all the old mechanics for 12 of expansions would present a whole new class of challenges to a team. WoW is a huge game. They already plagued by lots of bugs.
But this system exists for an entirely different purpose than a TBC server. It exists mostly to make sure low level content is still full of players, so that new players going through the story or players leveling up new classes can always find parties for dungeons. It also helps break the monotony of doing the same few current dungeons/raids all of the time
Note that in FF you have to do the huge main story quest on any new character before you can really access the latest content, regardless of how much you might level, and the main quest also involves runs through most dungeons. I should add that normally people only do this once on one character, since you can level all different classes (called jobs) on the same character - you can be a level 90 robe-wearing black mage if using a staff, and then you equip daggers and become a level 31 ninja in leather armor, or an axe and become a level 67 tank warrior.
> Even if you buy the expansion just to get the "feel" on how it was, it's impossible.
You don't buy previous expansions after a new one launches - they roll into the base subscription. After Shadowlands released, buying BfA separately wasn't even an option.
> MMOs like GW2 and even SWTOR do it way better
“Keep every expansion fully relevant forever” sounds nice until you think through what that actually means for an MMO like WoW. You would either fragment the player base across twenty years of content or turn gearing and balance into a complete circus.
Imagine your best-in-slot trinkets from the current raid and Siege of Orgrimmar, your tier set from Dragon Soul, the weapon from Hellfire Citadel. Try organizing a group when other classes need gear from Icecrown Citadel, The Everbloom, Argus and Ahn'Qiraj.
The point of "current expansion content is relevant" is that it funnels the player base into a fairly narrow area of the theme park. That is important, because if you spread out the population over 20 years worth of content, you risk making the world feel incredibly empty, which is a death sentence for a theme park MMORPG.
Blizzard’s actual approach is much more sane: older content comes back in controlled ways. Timewalking reopens older expansion content with scaling and relevant rewards, and Mythic+ seasons already rotate older dungeons into the current endgame pool. Midnight's Season One, for example, features dungeons from Wrath of the Lich King, Warlords of Draenor, Legion, and Dragonflight.
Blizzard’s actual approach is much more sane: older content comes back in controlled ways.
Well, here’s your problem. You need to fix that and eat whatever shit they throw your way, pay the money and say thanks.