Sorry Reboot but you killed Maplestory

In which case your suggestion isn't just to merge servers, it's to completely revamp the game.
You're saying, Nexon can save the game by telling all their most dedicated players, "We know you've been working hard to get 40 characters to 200, or at least 150, for Union. But we're going to delete 85% of them, because we don't know how else to get the hacking situation under control."
To avoid hiring more GMs, or developing and maintaining better hack-detection heuristics, or (Rhinne forbid) changing the game's architecture to make it less easily hackable, Nexon should throw away people's investment of time and money.
Sounds more like a way to kill a game than a way to save it.

Also, in terms of GM workload, a server alliance and a merged server are the same. If you go into any world in the alliance, you see all the hackers of all the other worlds as well.

Finally, what makes you think a whole bunch of alts and mules, which can't even be logged on simultaneously, increase GM workload in any way?

That is some fine trolling that you have managed there. Even after saying that the number I gave was an example and I confirmed that in the following post, you still presented it as the lower number. Clearly, if Nexon had the capability to merge servers without losing any characters then that would be the ideal choice. The amount of characters a single server can handle is limited however so there is no reason to expect that Nexon would be able to do something like that.
Maple has been going for more than 10 years, if Nexon has not been able to complete any of the suggestions that you mentioned by now, exactly how long are you suggesting that people wait for those things to happen?

Unless you have been a Nexon GM in the past then I dont think you are qualified to comment on what their work involves.

When I talked about a server with a lot of alts and mules, that was part of a question for what kind of a server would you want to play in? A server where most of the character slots are occupied by mules or a server where most of the slots are filled by other players?

It doesn't make any sense reducing player's character would affect hackers, the max characters they have is 2 if they are botters, and 1 if it's just spamming ones in FM/Craft town, they hardly create characters in the account, how this would affect em anyway?

Your sugestion is like when i imagined a price of a pro item, but it was worth 5x more than what i thought, i had no idea about the price of it, just like me you have no idea of the current game, and try to make changes without looking if it would even work.

I was not suggesting that character numbers be reduced, that was only a side comment to the idea of merging servers.
We all need to start somewhere. One of the first steps in gaining new knowledge is to ask questions. (I am also fond of trial and error)