We already had something like that, called Boss Brawl. Since it's been completely removed from the game, I'll let you guess how popular it was. People here don't care for PVP because it's just unbalanced, and the only way to change things would be to develop a whole different game
This is honestly the only decent point you made, but it's been suggested so many times it won't ever happen.
Also, keep in mind suggestions here in NA NEVER reach Korea. It's not a problem of communication, NA staff just doesn't care reading the threads, and I have my doubts Korea checks Koren players' suggestions
The Partholon Quests are AFK missions. You don't need to look for the monsters yourself, you just assign your level 95 characters to one of these missions and wait until the time requested is over. Other than sending the characters and waiting for them, you don't have to do absolutely anything else.
This post comes after a new package on sale in the depot, the New Beginnings Package, and especially one of its content, the Sentient Epaulet:
This is, to my knowledge, the first time we get something in the shop that gives a clear unfillable gap to cashers. Sure, we have Runes and Gacha already, but they only make life easier for people willing to spend money while f2p will have to take a more bumpy road to reach te same result. This time it's very different as the item offered not only gives a lot of stats (5 crit and 500 m/atk ruining rankings more than they already are), there is no actual other way for f2p to fill the gap.
At this point, there's only one thing I'd like to say:
Thanks Nexon, please make more items like this and my wallet will always be open