You're touching on something I've been thinking about for a while but it feels like you want Mabi devs to go all in towards changing the combat vs trying to preserve the old style.
You're comparing Mabi to League where League plays more like a Diablo-esque game and Mabinogi's roots are from a more slow/methodical playstyle. When you show your concept of enemy magic and attacks with telegraphs, it moves farther away from what Mabi was originally.
You say that the gray wolves aren't interesting but they are relative to the way the game was. The gimmick to wolves is that they counter a lot so you should attack them with Icebolt or a ranged attack to break their counter. If you got countered, you could learn or gain knowledge of the counter skill. It also showed that, because some enemies circle around you, not all enemies attack you right away, with the same attack over and over, like spiders. So unless you went to the school and learned icebolt, bought arrows and a bow, or found and did the quest to learn windmill, you had to wait for the wolves to decide to stop countering. This is all considering you were new and not being fed information from another more experienced player.
With enemies having exclusive telegraphed attacks, the game moves farther from the concept of enemies and players sharing a moveset. We already took a leap from that concept when they changed to the instant load-time dynamic combat system.
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Adding a dash is a band-aid fix for bigger problems, like how the devs are handling the difficulty in response to the damage creep they created, but it can cause problems too. For one, promotes a speed meta. We're already at the point where fighting is just one-shotting enemies and moving to the next group of enemies. Chainslash's crazy damage % and AoEs already promote that and it was a big mistake because it dwarfs every other skill set when not taking reforges into account.
In the game, Path of Exile, the meta right now is to go fast/kill everything so much so that the devs in the recent update, buffed a lot of content and made the game slower as a result. They added boss 1-shot mechanics, more mob enemies, added more HP. (Similar to Mabi) Alot of players hated this. Even casually, the meta is to get a flask that gives you a reusable speed buff, rather than more health or mana, to speed through the content as fast as possible. Then, when players are doing end-game content, suddenly they get killed without knowing what killed them. (It could be an enemy with reflective damage or an unfortunate set of modifiers like "Accurate+Always Crits+Fast Attacks") Adding a dash encourages the Mabi devs to continue making the content with the miserable one-shot AoEs you were talking about in the video.
At least for Path of Exile, while adding that difficulty slows the game down, it begins to resemble the way the gameplay was, early in the games release. Adding a dash and telegraphed attacks changes Mabi into a different style of game. And because it also promotes a speed meta, I can see the next thing being the knockback system being removed which is a big unique factor in this game. I can see them switching knockback to stun/knockdown, so you wouldn't have to chase enemies around. Knocking enemies back now becomes kiting enemies around. Removing potion poisoning would be the final nail in the coffin. If you want that style of gameplay, there are so many other games out there.
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So rather than adding a dash, I think they should add difficulty by rebalancing a lot of the noninteractive talents and give them weakpoints.
i.e Gun normals have low stun unless they crit. Now ranged weapon normals don't stun unless they crit (including chainblades)
i.e Chain Sweep, Crisis, and Climactic Crash can be defended
i.e Final Hit duration, cooldown, and reforges are halved (20/120) For players without FH reforged gear, it means it's up more but you can't abuse it for as long. So it's not a guaranteed room clear/boss killing move and it works better with Time Shift.
i.e Getting attacked ends your Fighter combo and Fighter cooldowns are all on a 15 second cooldown.
i.e. Defense cooldown gets lowered to 2 seconds.
i.e. Getting getting knocked down grants the player Adv. Heavy Stander for 1 second on get up. (Enough time to get up and windmill or evade. Useful for obnoxious multi-aggro like Sulfur Spider or Shadow Realm Champion. Similar to how enemies instantly get up when attacked while downed but balanced for the player.)
With these examples, the devs could start adding post fighter skillsets to more mobs without it being impossible to fight against. They could also stop gimping 1 handed swords and humans as a balanced measure.
Then, they could start implementing non-one shot mechanics and less spongy bosses. I think Claimh Solas, Mokkurkalfi, or Dragons are almost in a good spot for how big bosses could be handled. Mokkurkalfi needs a tell for when it does the AoE where you need to stand in the protective circle. Dragons need a tell for their stampedes. Swipes and tail swipes need to be blockable/counterable. There's a lot that could be worked on.
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In response to what you mention about cheese strategies. Outside of actual glitches and AI resetting (like group windmill spam), I don't think coming up with strategies that work is a bad thing. Like, Smash tennis from way back or Meteor Striking the Dullahan from outside of the room in Fomor Attack. It feels like you're outsmarting the game. Sidhe Finnachaid's Dragons being killable with magic feels fair considering the game is and has been melee-centric forever. I don't know if they introduced any enemies that are completely resistant to melee yet besides the ones that can color change like Nightmare. There are a lot of common enemies that always have a resistance to range and magic. In Finnachaid, the dragons can die to magic and the final boss has regen and is susceptible to wounds as well as there being enemies you don't want to be in melee range of or you get a long debuff. It feels like it was made with magic and range in mind.
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You say that Nexon either makes content too easy or too hard but the real problem seems to be that they're making content almost future-proofed for damage creep and reforge players. Getting to stat cap, having R1 skills, and having fully upgraded gear and weapons should be enough for late-game contents. There is a huge gap between something like Advanced Hardmode or Elite Shadow Missions and Tech Duinn. Stats are capped and skills aren't doing enough damage. Even on the Dungeon Guide it jumps from Alby Advanced Hard mode to Sidhe Finnachaid Advanced or from Martials Arts Finals to Peaca Abyss. Then new content comes out and it's just damage creep like Glyphwright temp buffs or Stardust procs on skills.
Nexon updated the combat system at the time they introduced the fighter talent, but did not update it for mobs. Before that, Mabinogi combat was much more difficult since we fought mobs on equal footing. Try logging into a pet and go fight things to see what it was like. If they put us back on equal footing by updating the combat system for mobs too and gave them access to the other talents, then they might be able to make fair yet challenging content without resorting to cheap tricks.