i don't feel like reading all comments so excuse me if i said something someone above me has already covered.
the game does lack a form of balance, and there's absolutely no unique to classes, most "mobile" classes are defined with not flash jump or teleport but triple jump and bigger/less cast time teleports (kanna is a weird one with huge range but also longest cast time)
there's no need for tanks or dps classes as bosses do % damage and AoE damage, so everyone essencially is the same, its not targeting a single person and dealing flat damage that can be reduced or redirected (for example to mana or functioning shields unlike AB's), there's no consequence to using potions during most boss battles like having to be out of combat or potions heal over time, making clerics's heal kinda useless and most classes have drain built in somehow, worst case you use aran card. (sure there's potion cooldown on end game bosses but usually they 1hko anyway..).
and every class nowadays is strong. meaning there's absolutely no reason to group up. in every MMORPG you're weak, from start to end, i hate to bring up the paste but i will anyway, back then the strongest members could barely pass 20k damage on mobs that's only x200 of what a level 10 could do. nowadays you start by hitting 100's at level 1 and end up doing dozen of millions if not hundreds and even billions depending on your funding. that's enough to solo most ****, so why would you share loot when you can make 100% profit? everything nowadays is inflated, when i started a fresh new acc in NA i had people give me free CRA item set because couple millions of mesos is just scraps for them. that's not that bad but it certainly takes from the adventure of the game.
nowadays there's no difficult, everything is just a matter of grind, 4 hours to make a mule to 120 (140 now) grind to gain access to content that you were dying to see as low level but already ruined the fun of it by looking at videos online because grinding to 225 is not really hard just takes a few hours of mindless grinding, basically everything is already far beyond dragged out.
and my personal most hated: decent skills. nexon has long realized, being the support sucks! and if its already neglected why not make it even more dead, so they added those skills, as usual first only for the whales who already long broke their piggy banks, and with the recent update to everybody! that method isn't new to nexon and soon enough there will be frenzys and broids all over maple but not before something even more crazy will come. for me this is a game of patience, 3 months playing 3 months break usually gets me all the goodies i had longed for while still keeping the desire to obtain all that soon to be crap...
conclusion: this game is a lot like mmorpgs but its over compensating and giving out too much free stuff so people find it hard to leave, but people will eventually get bored of it all, and when they will nerfing will have already been too late.