WoW was never particularly tough as a grind to begin with compared to it's predecessors. The grinds in EQ and Final Fantasy were far more brutal, and due to a lack of instancing technology allowing for a true hierarchical nature on servers, guilds were not interested in publishing strats for how to do things so they could keep an edge on being the only ones doing content.
Very different atmosphere to say the least. Humorously, as backwards as it sounds, it was also far more community building.
But a lot of people who played WoW never played any MMOs seriously before that, including myself, so they didn't have anything to compare it against. Also, at what point does a grind turn from hard or complicated to just tedious? I'm not saying WoW's raiding mechanics were more difficult than other MMOs, but some games that are supposedly hard are just mind-numbingly tedious.
EQ was tedious as hell by any definition you want to use - vanilla WoW was a breeze by comparison. Only a few select classes were able to solo - this changed with expansions and accrued gear but some classes never could. The amount of time it took to accrue exp for a level was ridiculous, there were also "hell levels" requiring a multiplier of the regular base for that level range of exp, certain races had exp penalties, and if you died you lost exp unless you were resurrected - the high level resurrections restored nearly all of your exp (96% iirc).
No quests either, so you would camp areas for exp and loot drops from enemies. Certain areas would have a chance to spawn a unique or rare enemy, and that guy would have a loot table - certain items had a % to drop. It was usually one item. The only benefit from this system is that really dedicated people were typically the only ones to hit high levels, leaving a lot of people you wouldn't want to deal with never getting so far
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If you died, you had to run back to your corpse with no gear, which is fun when regular enemies can kill you with all your gear on. Corpses rot after 1 full week (realtime) which was a problem in the very early days of raiding in a crazy zone like Plane of Fear. Necromancers were able to summon corpses by purchasing a component to allow them to do so.
Raid mechanics of WoW bosses were actually far more engaging and interesting than EQ or anything that came before it - almost everything in EQ was a basic tank and spank - it was mostly the competition between guilds that was borne for getting to limited resources (bosses) on spawn timers / after server resets that was interesting.
The game did end up with instancing and a lot of mechanics revamped to be much easier/less tedious as a consequence of WoWs imminent and subsequent release, as well as the following months and years
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