I think I found the problem

Contrary to popular opinion, it has very little to do with Pay to Win.  A much better way to understand the recent furor is the New Game Experience.

As you know, different players commonly like different sorts of games.  Even if we restrict to MMORPGs, this is still true.  There are different games to cater to different player preferences, so a lot of people get what they wanted.  Not everyone, but a lot more than if the industry just consisted of WoW and nothing else.

One group that isn't very well catered to is people who want winning to be based on huge amounts of grinding.  This is largely because there just isn't very much money to be made from games that target this crowd.  Most gamers aren't willing to spend enormous amounts of time grinding, and resent getting slaughtered by the few who are.

Having an elite crowd that pays tons of money for your game can work out, even if they drive other players away.  That's why there are so many games that cater to whales.  The grinding elite doesn't pay a ton of money.  They do pay something, but there just isn't enough money to be made focusing on a relatively small number of players who pay only an average amount of money per player.

Games catering to this grinders dominated much of the industry in the early days of MMORPGs, but this is an accident of history.  Early on, MMORPG developers hadn't figured out how better to bring in more players and more revenue.

Then along came Black Desert, which accidentally made itself a paradise for hard-core grinders.  This was completely unintentional on Daum's part, but they attracted a passionate playerbase of heavy grinders who would push away the masses without paying a ton of money themselves.  There just isn't enough money to be made from this crowd, so they decided to do something about it to try to additionally attract other players, especially but not exclusively whales.  Hence the change to allow item mall gear to be traded.

To many MMORPG gamers, this would basically merit a shrug.  In other games, I've often seen the tradeability of item mall gear lauded as a positive feature by players.  But to the crowd who thought they had finally found a game where they could grind their way to the top and no one unwilling to suffer through the same grind could compete, this was a total betrayal.

Daum made a change that most MMORPG gamers would either favor or (more commonly) be mostly indifferent about, but the ones who would be upset about it were disproportionately represented in their game.  And it's not just a higher percentage of the playerbase than most MMORPGs; it's the most prominent players.  People willing to grind a lot are by definition willing to spend a lot of time on your game, and that often spills over to being vocal on forums and other venues to express displeasure.

Hence the New Game Experience comparison.  And yes, that's a reference to Star Wars Galaxies.  The problem with SWG wasn't that the game was abruptly terrible after the NGE went in.  It's that it was different, and targeted a different set of players from what the game had previously accumulated.

It's like ordering a burrito and getting a cheeseburger.  It's not that cheeseburgers are bad, or worse than burritos.  It's that if you just spent an hour trying to find a burrito in a region where there are cheeseburgers all over, and are given a cheeseburger instead, that's not what you ordered.

Trying to dissolve the playerbase and attract another typically doesn't work well.  But if Black Desert losing some players who don't make much money for them allows them to attract others who will be more profitable but would previously have been chased away by the grinders, it might work out pretty well for them.

I absolutely would expect to see a major exodus of the hard-core grinders, and so a large fraction of the most prominent players will likely leave.  But that doesn't extend to the entire playerbase.  Most players in most MMORPGs know full well that they're never going to be one of the elite players with the best gear and everything.  Whether those elites got there by grinding, paying money, or whatever really doesn't make that much difference.

Black Desert tried to make an AAA sandbox game, with many things to do besides just combat.  People who are there for the trading and the life skills or other non-combat activities but aren't much into grinding aren't going to be too upset about something that messes up the hard-core grinders.  Indeed, if Daum subsequently eases the grind, a large fraction of the player base will probably see the changes as a net positive.  Just not the grinders who thought they had finally found a game that caters to them, only to have it taken away.