Low-level dungeons are ghost towns now because most of the leveling gear can be obtained from the Campaign quests. Nowadays, high-leveled, end-game players run these dungeons to farm Achievement points or costumes, which in itself isn't bad because it's fun, but ruins the value that came from dungeons when the gear from them was much more valuable than Campaign gear back in 2017.
That's correct. Being able to buy your way to level 60 [I think] came with the Legacy of the Hongmoon Clan update that was recently released months ago, and this was done to cater to the western gaming audience. Because westerners don't have enough time to play the MMOs they like to reach the latest updates released for end-game players, game industries that primarily make MMOs are doing this not only to make more money, but to allow their newest player-customers to "time-skip" the leveling process in their games and get straight into the action.
As a western gamer myself, I'm happy with this, and as it applies to Blade & Soul, it's fairly-balanced and well-designed, akin to many other MMO games that do this such as World of Warcraft, TERA, and RIFT.
That's entirely up to you. This is a question no one can answer but yourself because how you like a game and the time you're willing to invest in it is up to you. If you liked playing Blade & Soul before, I'm sure you're going to like it now, as long as you don't do the PvP, which is broken and poorly-designed.
Unfortunately, there remains the truth that this game has a P2W barrier when it comes to upgrading weapons and gear because most of the mats you need can be bought with microtransactions now; it wasn't like this when this game first released in NA, but it's changed dramatically over the years. Everything that you could buy could be earned in-game, and when you hit level 60, that's when you could start making bank with mats and farming them. Until then, you're stuck leveling to 60 through the Campaign. Moreover, since you've been playing since Soul Fighter, you can still catch up to the end-game fairly quickly by only doing the Campaign quests to level up because NC made it so doing the Campaign alone gets you to the new level 60 cap.
In the end, choosing to continue playing this game and finding out if it's "worth playing" is up to your judgement and opinion. Don't play a game you won't find fun or hate already because you'll only hurt yourself in the process.