To put it simply: you should coop this because Monster Hunter is the single greatest Coop game franchise there is and Monster Hunter World / Monster Hunter Iceborne is one great entry into the franchise.
I think no-one who played any substantial amount of Monster Hunter will ever read this, so i will try to address the Monster Hunter Curious.

Monster Hunter has an absolutely divine gameplay loop and has one of the best fleshed out „game worlds“ humanity has created.
The loop sounds simple : set out into the wilds, find a big bad monster – most times only one – fight it, kill or capture it, and carve its carcass get sweet monster materials (Horns, claws, bones, tails) to make better armor and better weaponry with them. Rinse and repeat. This loop is very confusing in the beginning and takes some dedication to completely comprehend and love – but if done you will be rewarded with the most motivating and complex action game there is.

Why is the simple loop so hard to get into? Because more and more variables are introduced. Monster have weaknesses and your weapons must match; monsters have special attacks and your armor and equipment must match; you can take capture equipment with you that has you luring monsters in traps and you have to gas it to be tranquil enough. Since monster hunter is an old franchise ( first game came out in 2004) and has around 20 entries the cast of different monsters is vast and they all have significantly different behaviors, fight tactics and tricks up their wings/or fins/or humps – and this is where we get into why the „game world“ is so great. The world is such a living and consistent space – the monster designs are incredibly creative and they stand out as real characters. The cities are populated with people and cat people – so called palicoes – and everything is very colorful and has a charming Japanese- fantasy vibe to it. The coexistence between, humans, cats and monsters is played very straight and although outrageous in principle works great and makes for nice quests, fun lore and likable inhabitants. Nevertheless the game’s story and the fate of you or the people around you are upstaged by how wild the wild feels, how monsters act like they should and how tense the fighting is. Fighting is one of the two main things you are doing, next to preparing (crafting items, forging equiment, choose the right loadout) and the fighting also shows that this fighting system was fleshed out over 20 titles: the game has 14 weapons now and they are so different that the game might as well as 14 different games. Learning a new weapon is a commitment – MH games can easily take 200+ hours to complete and each weapon can be played for 200 hrs since they are so complex and fun to master.

By far the best thing about MH is the Coop: It is just so flexible. You can play with a dedicated squad up to 4 people and play through the game together. But you can also play with other friends and help them with their goals or play with just a part of your squad and the person missing in one session can easily join the next session. If one of your squad did not get that fancy monster horn he needs to upgrade his ice elemental weapon he can go at it again,( alone, with randoms, with some of the squad or with other friends).You can also play the game totally alone, maybe just spontaneously join a friend or a random group when someone likes help with a monster. A great game to play in a bigger friend group and stay in touch,
The coop intensity itself is very dynamic and differentiates from making light chatting possible during some easier fights to very tense coordination and effective communication to make beautiful coop-actions possible during harder fights. You can basically play multiplayer or make the game very coop with a dedicated team tactic. There are so many ways you can assist each other: you can delegate trap duties, heal other people or give them an antidote, play the hunting horn to give buffs to your team, lure the monster away from your friend while he carves the loot out of a severed tail, take on different monster parts to break specific parts of your prey. The monsters in the endgame get quite tough and tricky and give the fine garments and murderous tools you have crafted throughout the game very good use.

Another triumph for this game is that it always has the dangling carrot to motivate you. Until the very endgame there is another Monster you can unlock or another upgrade you want. This is something where many long games fail for me. Monster Hunter over time and over several games (I started with MH3U) became my favorite gaming franchise – you should really give it a good chance and prepare for some setbacks.