That argument would be true if it was only skins, but it's not. I'm 100% in favor of games selling cosmetics, I love it when people who pay for cosmetics help to support a game I like, that's a win for everyone.
But what you've overlooked is that the pack for SE will also include a creature. A creature that may (or possibly may not, if you believe WC) give players an in-game advantage. If it doesn't give an advantage, any advantage at all, then it won't be P2W and will be good for everyone just like skins are. If it turns out to be 100% true that the new creature doesn't give any advantage then I'll be as happy as anyone else to see it added to the game. But if there is even the slightest advantage to owning a creature that people have to pay a fee to own, then that's a P2W feature. And, if that turns out to be the case you can be certain that WC will introduce more P2W features in the future.
That's the thing about P2W features, they start small and then grow. In every game that introduces P2W features they only get worse over time. The game rapidly gets to the point where people who want to win have to pay extra money to stay competitive otherwise they're going to lose even if they're good. And even when playing PvE it turns into a game where the game is designed to prey on people's impatience and (many) players pay money to beat the game faster. This is the economic model for hundreds of mobile games, punishing people with painful time barriers and selling them "solutions" that allow them to progress more quickly.
Even if this one element from my post turns out to be a non-issue, the other elements of my previous post are all still true. Shi Hai wants to morph ARK from a game into a platform, complete with a player-to-player market in which people sell things to each other with real money transactions to buy assets that make a difference in the game, with WC/Snail taking a cut of all those transactions.
That's the 'nickel & diming' I was referring to, not harmless skins, but creating an environment that punishes people with time barriers and "encourages" them to spend money to get past those barriers.