Let's get straight to the point. We should totally make the community's voice heard. But, always consider they are real people, a company, etc. It's their decision how they make money and the likes...
But with that said, I think it'd be interesting if you expressed your feelings towards the game, and more importantly, what could be improved. Tweaks, if you prefer it. Nobody likes to see a game halfway done, so it'd quite nice if small fixes were adressed.
Consider that KMS is a fairly accurate future, so add on to that. I'll start with my suggestions first then! As an example. I'll add more and more as people suggest them.
Create a user contribution site
Well, let's be fair here. Steam is a great company, that sets a failry impressive precedent. I'm talking about their Steam workshop. It simply works as a page where people adds their own submissions. Simple as that. But not just simple MSPaint cut and paste jobs... No, in their workshop, they include things that take almost no effort to patch in the game. SO, skins from TF2 become actual weapons ingame, and the creators get credic, and even reap benefits.
The way Maplestory is, people could simply draw all of the sprites of a weapon/armor/enemy/skill, in a file format the Nexon Team could handle. This way, people could even contribute FULL CLASSES, covering animations and all. And as for compensation, I'm quite certain most people would simply accept a gameplay incentive as payment. All depends on their ToS.
This way, everyone gets what they want. Both things implemented (could be new gachapon things, or masteria drops for all you know), and work saved!
Polish the monster book
This suggestion is quite simple. The monster book is stuck in its release. There's a lot to add still, and it'd be amazing if it was actually up to date. Main things I'm missing are:
-New sets and therefore stats
-New familiars (debatable, might not be that easy to implement)
As for the new cards, I'm not only talking about that new mud monster with a sprout over its head... I'm also talking about Zakum summons, for example, that would make not only awesome entries, but also awesome sets.
I'll list the cards I miss, either way.
-Muddy Sprout Monster
-Dark Monk (Temple of time)
-Dark Guardian (Temple of time)
-Dark Kentaurus (Past leafre)
-Dark Skelegon (Past leafre)
-Dark Cornian (Past leafre)
-Dark Wyvern (Past leafre)
-Chao, the ancient boar boss
-Elphine (???) the fairy queen from the past
-Fairy from the past #1
-Fairy from the past #2
-King Rombot, from monster carnival would be an interesting card to get, wouldn't it?
-Iron golem (Should have a special way to get, like dojo or monster park if it's accessible to everyone)
-Red spirit of rock, only in monster park, debatable.
-ALL singapore mobs. They were added to the book before, why not reimplement all of them? I mean from captain latanica to krexel. All the slimeys, truckers, and bersekies.
-ALL NLC mobs. Electrophants, Crimsom guardians, the twisted masters... Even trees if you push me.
-Why not add Zakum's summons to the list? It'd do great for a new set.
-Icy Mixed Golem
-Flaming Mixed Golem
-All Neo City Cards, too.
As you see, there's a lot of possible cards to be fixed, so newer players won't have to ask themselves, "why don't all monsters have a card?" Until an experienced player talks to them about how lazy and incompetent Nexon is :p