finished main quests of the game and started Iceborne

What? You've barely touched the surface of the game.

There is no story or even lore in this game. In terms of "fantasy world" development this game reminds me old arcade games.

The story has always been a weak point of the series. It has traditionally served one purpose and that's to prepare hunters for the real meat of the game found in postgame content.

However, I'd say the story presentation in World was a huge improvement from past games. It wasn't amazing, but it wasn't bad either.

Monsters ... they're just spawns in zones and roam around just to be killed, like cows. Yes, they can bump onto one another, but ultimately, they're just there waiting (yes, not for a long time) to be killed.

That's what the game is all about, no? You hunt monsters in a game called Monster Hunter. What were you expecting?

With all its finesse combat system - fights feels tedious and artificially prolonged (I'm not talking about min-maxed builds).

Isn't that to be expected though? You haven't even gotten that far into the game yet. You're obviously not going to hunt down monsters quickly without endgame gear.

Damage/defense/affinity/status/etc. systems looks like extremely convoluted... just for the sake of it.

It seems like game promotes abusing all its convoluted systems to efficiently progress rather than sharpening your gameplay skill.

Damn...why this game has SO MUCH consumable/single purpose items and micromanagement of them?

I agree the armor skill system and item management can be a little overwhelming, but they actually work really well with the game once you put in the time to get the hang of it. While the game does reward you for being well prepared for your hunts, the game is ultimately player skill based. No matter how good your builds are, you are not going to get far in the game mindlessly attacking the monsters you hunt.