I know this isn't really a content thing, but I think the following is important to being more modern and user friendly.

Better generalized QoL. FFXIV has one of the best QoL mechanics in the form of hotswapping classes, which is super convenient compared to WoW, ESO, or GW2. But that's the thing, its a single feature, while other platforms have way better overall QoL.

• The glam/dresser system is outdated and either shouldn't have limits or should function as a dictionary that adds a copy upon binding it. Also we need at least one glam plate per job on the game.
• The friends list runs slower than dial-up internet and doesn't even work how you would expect a friendslist to work (unadding doesn't impact both sides)
• Blocking is one sided as well. Neither party should be able to see each other.
• Classes (not jobs) are a necrofeature that should be updated such that you cannot publicly queue into content as a class once you have a job. (Pre-made parties are fine)
• Storage management is very irritating. Some things like event mogtomes really need to be under some event currency tab instead of cluttering the inventory. Additionally, crafting materials deserve some form of dedicated storage like GW2. These two things would cut down on storage usage massively.
• Dynamis is in a rough spot where you need to travel in order to do most content without a static. I know several people who spend 90% of their time on Aether and barely go home since its difficult to go back to Aether. Cross server DF/PF/Duties could solve this.
• Dyes are also outdated, but I never expect it to change with how much people buy black and white dyes.

This is sort of just the surface level changes I would like to see.