I played EQ2 from launch through Kunark expansion which was roughly somewhere in late 2007.
They experienced some dramatic changes - the start of the game was pretty much group required content. They had things called ^^^ heroic mobs. Sometimes they came along with little buddies that were weaker mobs that were ^ or ^^ type mobs. Basically it was dangerous to run around even green con ^^^. Worst of all, you couldn't "split" multiple mobs in one of those encounters. Either you took them all on, or the heroic would reset. There was very little creativity in addressing that from a player perspective. Either bring a group to handle the mob, or it wasn't possible.
Along the way, they changed that to make it more "WOW"-ish and it ended up from that change you could solo (generally via quest xp) from 1-60 in a couple days. I did this both on a troubador and an illusionist - both support classes (although both ended up being great dps on raids - so much so that my illusionist's ZW DPS on raids was in the 5-6k range, and on some encounters I was over 10k, topping out around 15k dps)
When they instituted AA's as we know them here on EQ, they were based not on grinding out xp, but on killing named mobs (that weren't grey con), discovering locations in zones (you got xp for that), discovering server first items and finishing quests. In effect, you had to do nearly every little quest to cap out on AA. You could get around the grey con named issue by mentoring which effectively means you were a superpower for your level and basically were powerleveling lowbies.
Further, with AA, you were capped at a certain amount you could spend (24 in each of the two trees from different expansion). In effect, you couldn't have every AA that was available, and had to strategically choose which ones to get. It basically came down at this point to which was the "optimum" AA setup.
Raid content was pretty annoying early in the game, as spells cast by raid mobs would crush a tank. They had issues where the ability to hold aggro was based off of casting buffs on yourself over and over to generate aggro and hold it. That changed, and it became a bit better to be a tank.
No complete heals - clerics cast reactive spells that healed the person each time they were hit. Shaman put a "ward" that basically had so much damage it would absorb (like rune) before it went away. Druids had IIRC a regeneration over time spell. Basically you needed to have all 3 types casting and recasting those "heals" as they faded from either duration or damage taken. In group content you could get away with just a single healer - but in raids you needed 3 with the MT and then at least one per group. Also to note, a Cleric and an Inquisitor were the same "class" so their reactive heals did not stack. Same went for the shaman and druid lines. So you couldn't have 6 types of heals on a main tank, only 3.
A lot of the raiding was stuff like, "Who has the yellow outline"? Go kill X mobs before they get to the raid mob or they blow up and basically wipe the raid. Epic raid encounters (avatars) basically was setup where you'd experience waves upon waves of mobs that you had to kill before the next set repopped. All the while, you needed DPS on the Avatar themself.
Instances were a HUGE thing. Think like... LDoN. There were named, and trash. You had no timer and could take as long as you wanted to clear it - but your timer to re-enter the instance was generally set at 12 hours for group instances and 3-5 days for raid instances.
Loot was Trash - Tradeskilled - Legendary - Fabled. Fabled only dropped from Master Chests. Master Chests generally dropped from named mobs and you'd either get a "Master I" spell for a random class (I think there were like 20+ classes) or a Fabled item. 99% of all fabled items were no drop, but the Master spells were tradeable - and there was definitely a market for them. I remember running the same instances day after day after day after day to get the drop I needed once I was raid geared out.
Tradeskills were much "easier" and was more of a game than anything. However, in order to tradeskill you had to harvest "nodes" out in the open zones. They were tiered from tiers 1 through XX, where each tier corresponded to the level tradeskiller you were. You couldn't fail combines in the same way that we do here (click combine, hope for success). You had to "massage" the tradeskill UI via a minigame using a handful of tradeskill spells you learn throughout the tier. Some increased durability of the item (to make it max quality), some increased progress (you needed max progress to finish the item and end the game). All in all tradeskilling was a one way road. You chose the skill you wanted, and that was it. You'd have to make alts to make other things.
Note in the beginning there was a TON if interdependency between tradeskillers. Alchemists had to make components for just about every other tradeskiller so they could do their combines. You'd get requests for 200+ reagents so someone could make a "run" at their tradeskill. Later on, they removed interdependency entirely and basically removed the market for tradeskillers to make money between themselves (my server even had a guild of JUST tradeskillers). When I left, 99% of the stuff made via tradeskill was crap with the exception of food and drink (which increases your out of combat health and mana regeneration).
Overall I think EQ2 was a great game, but when it became a solo/quest game, the market for tradeskills went the way of the dinosaur, and obtaining loot was based off of logging in every night, running 3-4 instances in as many hours and then logging for lack to do - I left the game.