Some ideas popped into my head, and I feel they'd be minor, but great quality of life changes that makes things a lot more convenient to the player without affecting balance at all.
1. Link Skill changes: What if each character that has a Link Skill were to have both the normal option to give the link skill to one character, but also give the option to give the Link Skill server-wide?
Pro: For this feature, you can give staple/must-have Link Skills to every single character on the server, such as the link skills from Kaiser/Hayato/Luminous/Phantom/Kanna/Demon Avenger/Demon Slayer. Very handy if you have more than one heavily funded class and thus becomes a huge hassle to change Link Skills each time.
Con: Since those characters will all get the Link Skill no matter what, some characters may want to fill up the remaining Link Skill slots with certain Link Skills, such as Cygnus Blessing if your favorite class needs that little extra status resistance for immunity, or the Mihile Blessing if your favorite class gets knocked around too much.
2. Trait changes: What if this was also server wide? The idea would be that you're on longer training your characters' traits, but in a way you're training YOUR own traits? The general thing I was annoyed is having to level up traits on every single character, and some of the benefits are pretty good. One way to make this work retroactively is to combine the trait values of every single character on the server. So if two characters on the server already have level 60 Willpower or something, the numerical value of Willpower will then both total up become say level 90 Willpower or something.
Since some of the classes already start off with higher levels of traits, one way to fix this would be as such: If that character hasn't already been created yet on that server, then the class gets a one time quest to get a trait boosting potion that increases trait level by the exact amount that class would have had without the quest. So creating a Mercedes would give you a one time quest for a potion to gain 11,788 Charm EXP. The reason for the quest is so the game can have a way to keep track of these quests being accepted, and avoid abuse from people who think they can delete and repeatedly create certain classes to power level traits.
Pro: Every character on the server will benefit, and helps people who plays more than one character. This allows the player to feel that traits are less of a mandatory hassle and feel like a true accomplishment when they finally get level 100 in each trait.
Con: Since it's server wide, transferring a character to another server means none of the trait benefits carry over. It's rare for a player to want to transfer their 200+ godly geared character, but it can still happen. Also as a possible negative consequence, the daily trait EXP gain allowable would be server wide. However, it's still a lot better than leveling all 6 traits for every single new character that you want to make.
Also, trait EXP gained from leveling professions may need to be have a daily cap so the rich can't just have up to 30 characters (it could happen) all max their professions and get to level 100 Willpower and Diligence in just one day. Hmm actually, I suppose this loophole may be allowed; if a player really wants to spend that much time and effort to power level 2 traits so badly, then more power to them.
3. Untradeable gear: This'll be short and simple in comparison to the other two. What if most untradeable gear was merely untradeable to other players but still account tradeable? Honestly Nexon, using Scissors to trade untradeable gear to other people is your main source of income anyways. Why make it more of a hassle for your playerbase?