How about some kind of iLvl Sync for CT1-3?

[Shougun]

All old content should get some update to become less stupid. Not really harder, not longer ; just less stupid. It's more noticeable with the crystal tower because it's easy to get it with roulette, especially since item level requirement can be abused, but old contents have become a mess. A boring mess for experienced players, and an incomprehensible mess for new players.

Most boss in the game starts with an introduction phase where attacks are used one after another, and it's only after that that more complex patterns and clever combinations are used and the real fight begins. But since fights become shorter, older boss die before the fight gets really interesting...
It's even worse with boss with special phases that take too much time with the current fight duration, especially when the boss do nothing and can be attacked (Cloud of Darkness)

The boss should be more active faster (for example : Phlegethon should use his bigger aoe right from the start), uninteresting gimmicks should be reworked or removed (Phlegethon flare, clouds phase with Cloud of Darkness, etc.)
For some boss, it can be as simple as increasing the damages (Thordan)

Personally I think in an average general sense it's good old content gets weaker at least to an "pretty easy" point (of the new to gaming perspective, not hardcore skilled raider "easy"). As it allows those who don't want something that challenging or time consuming content to be able to move through the game fairly well (also to note people still die to those easy mechanics/bosses referenced ). Those people who enjoy selecting "adventure mode" / easy in the options and still have a great time, which can honestly also sometimes be people who prefer normal / hard content too (personally would never pick easy option when first playing a game, but after I beat the game I usually come back with cheats or mods and just mess around like in Skyrim because eh why not).

So I think allowing content to nerf itself over time allows the content to be played by a very large variety of players, starting it out harder for those who prefer the challenge and slowly becoming easier to those who just wanted to experience the movements through it as if it was an adventure mode.

Though I do agree there can be times where you just wonder if the content should complete itself, when everyone gets a level that they're all super familiar with on jobs they're way over synced to.. then it's like auto run till you reach the exit lol.

Also agree that it could be fun to encourage players to feel that challenge for old content again- so in that mind:

While I don't really think they should re-tune much in old content to make it harder for the normal content flow, I do wonder if there could be a good amount of fun and challenge in a new daily/weekly roulette (roulette in mechanical sense, not really "random" but does rotate weekly). A new rotating set of challenge roulettes. Perhaps starting with three for wider selection, two cannot be from the same content format (if one is dungeon the other cannot be dungeon, and will be trial, raid, alliance raid, etc), and the final third one will be exclusively rolling very hard options (if not EX/hard raids it might roll a normal dungeon with a boat load of modifiers to bring the pain), should probably come with a warning lol, and allow full party queuing (would probably be a strong PUG killer duty queue).

These challenge roulette coming with a much tighter sync, regardless of how high you are, and new mechanics. Some new mechanics could be more aggressive AI, more packed enemy layout, new boss moves, or even just modifiers like prefix/affix changes to content. One modifier for example might be sometimes in Garlean theme'd content it has a chance to roll dropship affix / prefix to the content piece- which causes sometimes, even during boss fights, a group of garleans to dropship in (picture FFXV dropship, big landing party). Some modifiers being general (any content), others could being type, theme, or even content specific- like for the Tonberry dungeon you might roll that the Tonberry never stop following you- ever.

The rewards being split into two groups, an enhanced base of the dungeon, and then the one time roulette reward we all are familiar with. The enhanced base allowing you to make it semi-farm-able for low/medium tier tomestones and exp (not as good as other one time roulette bonuses but good enough to not be a waste of someone's time, if they loved and wanted to repeat the roulette). Then the one time a week reward we all are familiar with on roulette could be a mix of current cap tome stone and perhaps a unique currency you can spend. Besides for glamour and some material items/songs maybe float the idea the currency can become wild card currency (giving it a much longer life span, that grows over time), like you may spend it to become wolf marks (basic pvp currency) or any OLD (never new) primal tokens (amount trade ratio based on age of primal, but since this is three roulette rewards locked at once a week it should probably be more than 1 token lol).

Since they'd be picked each week SE could even have some hand in the modifiers to the content. Making a better theme and balance (although too much time shouldn't be spent on finding the perfect mix of changes). Just one note, at least personally, I hope any HP modifiers a content might roll are not very large and maybe coupled with something else like back up healer monsters instead- HP sponge is one of my least favorite ways to make something harder. Also to note this means the currently buffed content piece would be known the rewards shown, no secret.

From that I could imagine on one week you might see Praetorium getting auto-skipped cutscenes, alarms going off non-stop (causes guards to spawn from set points and run to you, at an intense interval), bosses being able to call in backup and summon all currently alarmed guards (so those spawn and training to you mobs /all/ being dragged into the room like a swarm of nightmares), the tight gear sync causing bosses to hit harder and die slower, enemies are able to use elevators (or at least go through the floors to chase you), basically collect all the rage from unskippable msq cutscenes and turn it into a dungeon buff .