-Game balance. Part of Terraria's appeal is the large variety of viable weapons and other equipment available to the player at each stage. Introducing new equipment that greatly outclasses everything else in its tier reduces the variety of equipment that the player is likely to use; rather than making the game better, this would make it worse. A few other things to keep in mind, though
A LOT OF DEMAGOGUERY, SUBJECTIVITY AND POTATO LANGUAGE INCLUDED
It's been a 6 years, 2 major upgrades have been released, and what we got in the current endgame:
- 4 sets of armor, one for every class, just like in 1.1 era, when there was 3 classes (it's actually a single armor with different helmets), that mostly outclasses other armor (Solar armor, that already used to be powerful, got major buff in 1.4, and outclassed Beetle armor, definitely)
- OP gun for Ranger, SDMG,
that eventually buffed in 1.4 because it seems it used to be a weak weapon lol, with no spread and which DPS is in one and a half bigger then second best gun in the game, Vortex Beater; Celebration MK2 (both of them are in same tier as Vortex Beater and Bow)
- Vortex Armor that duplicates Shroomite armor, but with bigger bonuses
- 20000 DPS Sword that can kill Munlord in 12 seconds (SDMG raw DPS is about 2000), probably the apotheosis for 1.4 update (same tier as Solar melee)
- Death beam of death for Mage, probably the apotheosis for 1.3 update (same tier as Nebula magic)
- UFO Mount (CCK) that provides infinite flight without losing mobility and doesn't occupies slot of accessory. It even frees one of the slots because you have no reason to wear a wings if you fighting in open space, especially against Celestial Towers and Moon Lord
And the most important: No locations and lack of events to use all this stuff: Dungeon, Frost/Harvest moon and Old One's army (even if it added in 1.3 era) are adjusted to 1.2 content, you'll just destroy everything and everyone, and nobody can't hurt you there, unless you playing on
Master mode artificial difficulty. The only event that may be challengeing is a Celestial Towers event.
Sure, similar things have happened before 1.3 (Chain Gun that outclassed Tactical Shotgun, Beetle armor, Snowman cannon that outclasses literally every ranged weapon, Night's Edge that outclassed every melee in 1.0 era), but in 1.2 you actually have much wider opportunities to customize your character and equipment to choose (even Hallowed armor was someway viable and Shroomite armor have quite low bonuses without stealth, unlike Vortex, etc etc), and it wasn't necessary to add another tier of the game while they could adjust stuff after Cultist to 1.2 level: for example, Vortex should not be Shroomite armor version 2.0 (more like version 1.3), or SDMG shouldn't be changed at all (it used to have 35 damage and use time of 6, and it's fine because it has no spread). Most examples related to Ranger because it's my favorite guy
So it goes. This is my opinion about current state of endgame, and while things like Zenith, Celebration MK2 and Last Prism are still exist in it current state this rule doesn't have any weigth. It's
highly subjective, it's fine if you disagree with that