This turned out longer than I thought and hoped, but I had to share my (annoyed) thoughts on this somewhere so here you go. If you do not want to read my rambling just skip to the ideas.
OUTLINE
I think, despite the (in my opinion justified) backlash, most people would agree that the rates were a bit on the high side (with people reaching 800m/hr on 1x). Furthermore I think it is undeniable that non-KMS dropping meso outside level range was unintentional on Nexon' s part. Therefore I also think that most people are not necessarily mad that non-KMS maps were 'fixed' but they are mad that there is virtually no alternative that provides a decent pace of progression, not fast, just decent. (Sidenote: decent progression rates always will depend on how much time you want to pour in and therefore will differ from person to person. Decent progression for an average player will always mean fast progression for a hardcore player and slow progression for a casual player.)
MAIN ISSUE
In my opinion decent progression should be possible at all levels and stages of the game, this is what keeps the game interesting. I think this is currently one of the biggest issues. Place yourself in the shoes of a new player on Reboot. The first few levels are quite easy and after that it gets harder and harder, but we all know you can still progress decently quick. Levels 190-200 for an entirely new player may take some time but that's alright - he is progressing. Then, this player hits 200. Wooo! 5th job unlocked, all new training areas. However the jump from twilight perion to vanishing journey is very steep, if I may draw from personal experience. It is, I think, at this point most people realise their gear hasn't been keeping up with their level and they should start to farm. This is now no longer an option. Unable to get meso or nodes, as VJ mobs are too strong to effectively farm, without a kishin mule or meso/drop gear how is this player supposed to progress at a decent pace? Daily bossing seems very slow, taking weeks or months to get the gear required to even farm at VJ. I think first and foremost this is the biggest issue of all. It unreasonably slows down progression for new players.
Now what would allow for this decent progression rate at all stages?
In the early game levelling and getting your standard gear is the main form of progression. I don't believe anyone thinks this part of the game needs dramatic changes. Levelling to 200 is pretty doable and obtaining some good gear is also not an issue (CRA, Tyrant cape, Sweetwater, Commerci, Gollux).
Then in the mid game progression is mostly about your nodes, arcane force and potentials. I think this is where the changes made the biggest impact. Getting AF is still doable with dailies, so no issue there. However both getting good potentials and getting a decent amount of nodes are now exponentially more difficult (nodes since most players cube dropgear especially for farming nodes). With meso farming as we knew it gone and these player having no good alternative of obtaining either mesos or nodes I do not see a way for these players to progress at a decent pace.
Then in the late game progression is mostly about perfecting the previous things- max out your nodes, perfect your potentials, get that umbra weapon, doing arcane dailies - and starring your tyrant items. Admittedly I am not an endgame player but from what I heard endgame players (with a kishin mule!) still get decent rates. However, even at decent rates (400m/hr) it would take an expected ~40 hours of meso farming to 10 star a single tyrant equipment. Now it is arguable whether this is decent or not so I will not go too far into this, since I am also not too familiar with true endgame.
IDEAS
I think the alternative to meso farming should ideally be something that is not a once per day type of thing, like Ursus or bosses. In my opinion I think you should allow players to grind out a multiple hour farming session if they wish to. Some ideas are already mentioned, like increasing the amount of meso arcane river or scrapyard/black haven/DWT mobs drop (and not by a measly 10% or something). Alternatively it could be possible to avoid the meso farming together and allow players to obtain cubes in other ways (let elite monster drop a guaranteed cube, increase cube drop rates from bosses, increase legendary vein spawn rates). But much rather I think players would have an effective way of farming meso. This can also be done by increasing the amount of meso an elite monster drops, by increasing meso drop rates for all monsters, by increasing the value of spell traces/twisted times or by introducing (repeatable) (party)quests that give a considerable amount of meso (hint; we're not talking in thousands here).
Other options could be creating a buff/potion like wealth and legion that much more dramatically increases the mesos you obtain. Even getting this from a daily quest and it not lasting very long is okay in my opinion, as long as it does not expire. Another (perhaps unlikely) idea is to create something like meso-land, where mobs around your level spawn and drop a lot of meso. There could be a trade-off here where for example the mobs do not give any EXP or other drops. If Nexon wants better control of the rates they could even make it so that you get a set amount of meso for every kill you get, or maybe something like monster park EXP - this would truly close a bit of the gap between starting and endgame players, since meso gear would no longer be a necessity.
