Listen, I think FFXI is
by far the greatest game ever made no joke, but I would never want to go back to 75 cap despite all the great memories I have of that time. Yes you had a great sense of accomplishment when you finally beat impossibly hard fights but you also had tons of agony and frustration from all the losses that came before. Since the cap was raised so many quality of life improvements were made to the game that make it much less frustrating and time consuming to play. Back in the 75 days it took so much time just to get anywhere be it by chocobo, ship, airship or even mage teleportation. You literally wasted hours upon hours every day you played just traveling. The game forced you to cooperate almost constantly in order to accomplish anything, even the most basic tasks and while that was good for building camaraderie with others, it often left you extremely frustrated when you couldn't find somebody to help you do something as simple as open doors (some of which, in certain dungeons, required multiple people to open).
FFXI was also extremely elistist back then seeing as how difficult it was, people got very upset with players that "messed up" or didn't have good gear. Also camping HNMs was very time consuming and with the rampant cheaters often extremely frustrating. It was a lot harder to make Gil back then too, especially for the average player. For them it would require endless hours of farming near worthless items. The whole game was just one giant time waste filled with endless frustration with the occasional moment of greatness when you achieved your goal making seem like all the rest was worth but it's just the endorphins playing tricks on your brain.
When Abyssea and the level cap increase were announced a lot of players quit and I was one of them, believing that the efforts I made to get the best gears would be reduced to nothing as they would soon become obsolete. After a year of pouting, I decided that I should give it a try because what was the point of staying with the same strength with the same gears, I realized it was good to try to reach greater heights with all new gears. As I started to play I realized Abyssea was really amazing and so much fun and it could be low-manned with 2 to 4 people if you couldn't get a full party together which was great. Abyssea tied in really well with the previous storylines as it blended the parallel worlds introduced in Wing of the Goddess with Chains of Promathia's story where Abyssea was a parallel world where Promathia became Shinryu and killed most of the FFXI's hero NPC characters that helped you beat him (including you) in your Vana'diel except for Prishe. Walk of Echoes and Voidwatch were great end-game additions at the time as well. Fighting Provenance Watcher with a full alliance was quite fun.
The cap was 99 now, but everything changed again as Seekers of Adoulin was announced and although the 99 cap wasn't changing, you would actually gain increased level power via gear now, which made all old gear completely useless as they lacked the level raising attributes, particularly all weapons which lacked increased skill levels which would mean constant missing if you fought anything except the most basic of Adoulin monsters. This was a tough time for a lot of people because you couldn't get the level raising gears easily, especially the lv.119 ones which were the best and made you the equivalent of a lv.119 character if you had a full 119 armor set and weapon. Most groups doing Delve, the content that rewarded you with the best 119 gears at the time, were elitist and required people to already have 119 gears to participate, at the very least if you were a DD, because Delve was very hard back then and really to win within the time limit, you needed to have DD that could damage the final boss. Seeing this SE introduces new armors that were easily obtainable that were lv117 and made if easier to participate in Adoulin content.
The Adoulin storyline was great and SE was done and released a free final expansion Rhapsodies of Vana'diel that tied all the storylines together and it a great way to end the game. They added fantastic endgame content in the for of the Escha zones, Vagary, Incursion, Omen, Sinister Reign and Ambuscade (easy way of making Gil or getting great gear for the average player) among others. They added so many quality of life improvements that make the game a joy to play rather than a chore, you can get around easily and they added the ability for your favorite FFXI NPCs to be summoned to your party to fight alongside you and this is the best feature they've ever introduced despite what naysayers think. You often have to do quests to unlock them so that's fun and while they are a great help they won't replace a good player, but they allow you to do certain things solo or low-man which would otherwise be impossible or much harder. That doesn't mean they'll let you do everything, far from it, they mostly allow you to do the storyline but most endgame content can't be soloed using them. SE introduced Job Points, a new form of experience points you can spend to make your job stronger, once you have max out a job's job points you become Master and have the 3-star Master logo over your character name. These job points are very slow and tedious to get and the fastest way to do it is in a full party, so if you miss old school leveling, it still exists today in the form of Job Points.
Also since the 75 cap SE has done a pretty good job at balancing the jobs. Black Mages and Scholars were mostly irrelevant at 75 but became extremely powerful since SE significantly boosted Magic Burst damage. On Black Mage you can often Magic Burst tier VI nukes or Death for 99,999 damage with the proper buffs. DDs now attack so fast that it is pretty easy to self-skillchain on most DD jobs. Blue Mage, which is my favorite job has become a melee DD powerhouse but also a potent nuker (especially aoe, BLU aoe nukes are actually way better than BLM aoe nukes). You can actually self-skillchain on BLU, then Magic Burst your own skillchain. It's pretty cool. Melee combat was so slugish back in the 75 cap days, now it's is incredibly fast thanks to spells like Haste II and so much Triple Attack gear available. I could never go back to the slow combat of 75 cap. The animations have trouble keeping up you attack so fast now. Also the new job that were introduced in Seekers of Adoulin, namely Geomancer and Rune Fencer are both fantastic jobs and I couldn't picture FFXI without them now, especially Geomancer. So much of the great game that is FFXI today would be lost at 75 cap
In short FFXI has never been better than it is now except for the lack of players but that's hard to escape for such an old game and with FFXIV being out. But FFXI and FFXIV couldn't be more different from eachother, FFXI is a real FF game at its core, with MMO elements added whereas FFXIV is a WoW-like MMO at its core with FF elements added. Looking back at 75 cap without the nostalgia googles on will reveal that the game was mostly a chore and the only thing that made it playable was the great community of people. If anything there should be a petition to have SE remake the current game with a new graphics engine and voicing for the cutscenes and have it F2P. They could easily make a fortune on costumes alone like Fortnite does.
There's so much more I want to say and improvements i want to highlight but I feel like I've rambled on enough for now and just in case you think I don't know what I'm talking about, I have over 18,000 hours of playtime on FFXI (that's like 2 years of my life):
Keep in mind this playtime is over a period of 12 years and that I sometimes stayed logged in all day when I wasn't playing to bazaar things or just cause I didn't want to have to log back in, which is a hassle. Most of my friends and family had no clue I even played it. I didn't really play any other game though, so most of my gaming time was spent on it rather than playing a bunch of different games.