I'm mainly nostalgic about KPQ and LPQ. Looking back on it, I don't get why I found it fun. In the same way I don't get why I find Horde and Firefight so fun in Gears and Halo (haven't played past Reach though), respectively. It's the same thing over and over, but with different people. I think I just liked working together with others towards a common goal. Was also fun to meet and talk to new people. Made a lot of friends through LPQ especially.
The boat rides were great, too. The Victoria/Orbis and Orbis/Ludi voyages were the only ones I ever really saw people in, though. Most went afk, but there were always a handful of people to talk to.
I also miss the population, and just being a kid again ;_; I used to complain about school, but goddam was it a lot easier than having a full time job. College, especially, was the most expensive vacation I ever took. Maybe I just need to settle into it more.
As far as immersion... I never really felt it with MapleStory. I could just be spoiled by RuneScape's great writing and world-building. I will say that I really really enjoyed Heroes of Maple, though. One thing that sort of turns me off in MapleStory is the amount of anachronism. It's been there from the start with Kerning City and taxis, but got progressively worse with things like Edelstein (I don't count things that don't get referenced in the fight against the Black Mage, i.e. Omega Sector, Singapore, etc. unless they have been and I'm just not aware?). It's not that it's bad content - the Resistance classes are pretty fun. It's just that it detracts from the medieval setting, seeing a warrior in plate armor next to a modernly-dressed person in a high tech mech. That's just how I feel, though.
Haha, I actually really enjoyed that minigame when it first came out. Never played LoL or any of those big name MOBA's though (closest I've played was Hero Attack on StarCraft II lol). And I stopped when I came back cuz it always took too long to find a match. Plus, One Card was semi-afk-able, effortless, and way more populated.
I wouldn't mind it returning as a periodic event, with decent enough rewards to encourage a lot of people to play it (cross-world play would also be nice...)