At this point Sorrow, I doubt they ever will. It's pretty difficult to balance something like that. Generally for a large portion of Maple's existence, if you are strong, being solo awards more exp than being in a party. So it is inefficient to party with other players, especially if they are weaker than you are (and even if they are stronger, they are getting more kills, doing more damage, 'taking' more of the exp). If they were to make party play truly viable, they'd have to hit the nail right on the head. Otherwise it'll be stronger than farming alone and everyone will just mandatorily group together arbitrarily and then proceed to play solo, just all together on the same map. It's difficult to get something like that correct, and Maple honestly never really has. No arguments here though, I just accept it as part of the game. I prefer party play more anyways. Every second solo where you are taking a drink or itching, or adjusting your position in your chair, you are wasting exp, and I hate that feeling. In party play, you (as the other member(s)) get the liberty to do all those things, and so do I. Much better for a grind-focused farming session in my opinion.
Honestly you people clearly have no concept of what exactly goes into releasing something like this. Maplestory targeted children with it's style so there is bound to be some brats out there but good lord. Many of the remaining players (and players bashing maintenance) really need to grow up. You can check, double check, and triple check every variable, and something can still go wrong. Then you have to set about finding the one random thing that just so happens to be not functioning correctly.
People here have no concept of what goes into a troubleshooting process and cry because they can't play the game. If the initial maintenance had gone this long, the frustration would be warranted. But it wasn't. The game came up, something was wrong, and now they have to fix it. Such is life. Just my 2 cents.