This has probably been repeated multiple times already (from what i've seen from older posts),but..
I believe,the main things that need to be done/fixed is:
-Something to stop leechers from getting free exp from doing nothing with really high level players.
Suggestion: Just as people are stating above,it's not bad that the player is being "trained" by someone powerful,but they should do something to help killing a specific monster,and get the exp desired by how many hits/damage he's done to the monster. Simple.
Anti-yesterday,i've found a field boss and tried killing it with party members,but a random over-powered player came in and just one-hit him (He was almost dying by that time) and he got all the exp,literally. None of the members on my party got anything.
-(2nd) Trading System. I don't need to say much here,it's really sad. The gacha already works horribly,you pay lots of money (depending on how much OC/Tickets you get) just so you get a random item from a specific unit. That's really BAD,all everyone has is bazaars,but they also need OC to work,and apparently there's TAXES with more OC? Really?
Suggestion: Just make it like many other RPGs do,trading items safely and FREE,this game already has it's unic feel that's making me stick around longer,but it's still really broken,it's missing so many basic things. Charging people for a basic option of any MMORPG is a flawless logic.
I know that major changes might not come so quickly,and you need approving from the JP devs,but i'm halfway sure this kind of thing must've been fixed,if not,then I don't know how this game is still going.