My first MH was MH Portable 2nd G on the PSP all those years ago when a partial English translation came out. I had fun with friends but I remember getting tired of the grind after awhile, despite feeling the game was very special.
I get some of the Japanese and North American titles confused; is Portable 2nd G the same as Freedom Unite?
My first Monster Hunter game was Freedom 2 on PSP and although I was amazed by the game, I remember hitting my first wall and putting the game down in frustration, then returning it to the store to buy a different game (back when that was a regular part of life for gamers). A few months later when Freedom Unite released I bought it, thinking to myself that although it proved incredibly difficult I did very much love the gameplay and the art style, so I figured I'd try it again. My daughter had just recently been born about a month before the game released in North America, normally my memory is terrible about these kinds of details but because it came out so close to her birthday it stands out for me, and I spent many hours sitting on my old sofa playing it in between tending to her and her mothers needs. I was also an addict still back then but that is another story, though it is for me an inseparable connection with the game.
Anyway I fell in love with the game and it was an obsession for quite a while, and I was determined to clear all of the G Rank quests including the online tiers despite never once playing the game in multiplayer mode. I agree whole-heartedly with everything you said about the old games when compared with the new and have gotten into numerous arguments about it with essay length posts on YouTube in the past, invariably being grossly outnumbered considering my take on and preference of the originals are not popular opinions.
The older games I feel had an intangible, practically ineffable quality to them that are either outright absent or are present only as pale simulacra in the newer games, particular in World and Rise. Things you've mentioned already, such as the necessity of preparing for the more difficult hunts, and the limited inventory space made the game feel much more engaging, far more challenging and thus more rewarding. For instance I mostly used the Light Bowgun or the Bow back in those days, and my primary melee weapon when not adhering to my gunner playstyle or just to change it up a bit was the Great Sword, followed by the Long Sword. When you hunted as a gunner in that game, even on high rank village quests but almost always on high or G rank hub quests, you would consistently run out of ammo before felling the monster or even weakening it to where a capture becomes a possibility. This required that you learn how to craft your own ammo and each kind had its own recipe, while each monster had beyond their weak points certain elemental and material resistances which only by inference through trial and error were memorized. So given the limited inventory space you really had to be selective and forward-thinking in preparing for a hunt, especially once you acquired the powertalon and armortalon, crafted the charm variants of each and reacquired the base state items to make maximal your attack and defense before considering things like charms and consumables. And then there are the Combo books, which together with the talons and charms occupy precious inventory space yet when you run out of ammo they become absolutely vital.
So you would bring in your bag not only the maximum amount of ammo for each type, but the maximum amount of the crafting ingredients for each type, and with hub quests very often even these would be exhausted before taking down a monster and required scouting the environs looking for more materials. This really heightens the intensity of the hunt, especially when low on health, out of ammo and any healing consumables, but makes for glorious exhilaration and induces a desperate survival mentality. Those hunts that end with you firing the last handful of projectiles you have, with a minimal amount of health left which would see you cart a third time in a single blow, the clock running down with mere seconds remaining, are among the few times in my life I've actually leapt up out of my seat in exalting triumph, beaming with euphoria yet trembling like a leaf from the adrenaline and anxiety. Not even the Souls games have proved so visceral.
Much was lost in the streamlining of the core gameplay loop and the emphasis on the multiplayer mode, to where the single player games now resemble Skyrim or Fallout 4 in that they are only superficially similar to their predecessors. Hunting monsters now feels like taking a ride at a theme park, the way Fallout 4 presented its gameplay and minimal reactivity among its set pieces culminating in the penultimate postmodern caricaturizing of its own burlesque projection of its self-image, the amusement park made manifest literally in the final narrative DLC Nuka World. Rise is a decent game, but it isn't a masterpiece the way the earlier entries but especially Freedom Unite, 3U and 4U were. My own personal favorite is Portable 3rd which was only released in Japan, but back then while my cousin was still alive and hacked my PSP so that I could use it as an emulator and so forth, and I was able to play that game in Japanese, which given the similarities to Freedom Unite made translation pretty much unnecessary. Gone is the way the ferocity and sheer animal terror of the hunt and melancholy locales (the swamps, or the deserts at night) was tempered by the merry-making anime sort of hyper exaggeration that greeted you upon return to the village and especially the farm. The absence of the farm in World was one of the more egregious changes, replaced with a tiny and streamlined patch of earth right next to the market where the process of growing crafting ingredients is reduced to swift few button taps as you pass by in between quests. Seeing the farms in Freedom, Portable 3rd and Tri slowly accumulate in size and possibilities along with a growing population of felynes and other fantastic creatures was one of the best parts of the game, making the down time between hunts, gear-crafting and grinding for materials so much more welcoming.
I did play World when it first released but never bothered to try the expansion because of how put off I was by the many changes to the format I'd become so fond of. The fully open hunting areas was neat and some of the actual hunting mechanics were improved, but overall the story was abysmal and there was far too much of it, while nothing about the characters or environments made me "feel" anything significant. The graphics were certainly impressive and the movements and monster designs truly awesome, but ultimately it just didn't appeal to me the same way. And although Rise was somewhat a return to form, or at least to the portable form, the new hunting partners that you ride on (I already forget what they are called) completely changed the dynamics of hunting and made everything super sped-up, removing the cautious approach and tracking that was critical to some of the older games. I've since tried all of the original PlayStation 2 games by emulation and all of them just have a very different tone, one which I sincerely miss. With Rise I don't even remember how far I'd gotten before I bounced off of it, but I still own it and have a Switch so eventually I intend to finish it and try the expansion. I just don't expect they will ever manage to recapture the spirit of the original console and portable games, and due to the immensely greater success they've had with the newer iterations, it is almost certain that the effort to do so no longer even exists.