Exactly how many MMO's have you played? I can tell you that nearly every MMORPG has been copying WoW since EQ fell out of favor, but EQ came out when FF8 did. Ultima Online and NexusTK were the two games I tried during beta's but the hardware requirements of UO (and then later EQ) were always too high. When the large cities have 1Mbps Cable Internet, and you're stuck at 28K Dial-up, MMORPG's are pretty damn terrible to play.
Each MMORPG came out after a certain piece of the hardware puzzle fell into "everyone can play":
UO was a 2D game that came out in 1997 AND IS STILL GOING. At launch the game was about as visually impressive as Ultima 8. It's longevity owes a lot to player-investment in time. You (currently) need a 400Mhz Pentium II to play it and no 3D accelerator. At release the fastest CPU available was a Pentium 233-MMX.
Everquest was the first 3D MMO to become popular, it's visual quality was actually high for the hardware at the time in 1999. It is ALSO still running. When people talk about tank/damage/healer/support classes, this is where it comes from. But this is also where the "Turn based RNG" comes from, that "familiar" hotkey bar (which actually came from Diablo)
What has changed substantially since is the compression of inventory (Diablo had a "tetris" style fit objects into your inventory, Ultima just let you throw things anywhere thus was a mess to sort) The idea of multiple bags, also came from Ultima 6.
Current MMORPG's due to widespread "dupe bugs" have been scaling back the inventory space (or have been using it as a cash-shop cash grab,) and FFXIV is the least generous when it comes to inventory.
Larger inventories also requires far more bandwidth, because everytime you opened the inventory window, the game had to transfer the complete contents over the wire. Every time you changed something, every slot had to be checked again.
But as for "what are MMORPG's copying from WoW?" Probably the dungeon-crawling pace. I've never played WoW, but I can see pretty clearly where "things have been copied from WoW or EQ" because they copied the UI representation in exactly the same way. For example SWTOR's inventory and Wizardry Online's inventory made use of the "one icon represents 30 some odd pieces of gear, only with a different color grade", FFXIV doesn't reuse gear nearly as much, but it certainly does enough that a lot of "materials" have to be checked before being disposed of because you don't know if you're throwing out crafting materials or Alexander weekly rewards without checking closely.
V1.0 was unfinished, and I don't buy the excuse Yoshi-P gave for why it was copypasta'd. They said it was so that the world was seamless, but it seems the true reason was that they had separate people working things, with "field design" somehow outsourced to China and they got exactly what they paid for. Look at anything else in V1.0, and a lot of care went into the game design. But somehow it looks like either one person copy-pasted everything, or they left it to an algorithm that just randomly picked "premade" tiles and then picked random biome-specific textures. It's not unprecendented. Games like Minecraft, Everquest Landmark and even going back to StarFlight, did it, but even then, some care was spent into actually making what you got have a reason for existing. FFXIV's V1.0's landscapes once you got outside the 3 cities felt empty, like not even a "front line" of exploration and discovery, but more like "we ran out of budget, here's a tent" Something I remember from those early V1.00 days was several "airship" landing spots, but no airships.
A game that has lore, has to have a reason for the landscape to take the shape it does. A game like Minecraft (Starbound and Terraria too) or Starflight does not, because the landscape generation algorithm isn't taking into account plate tectonics, volcanism, hydrology, or erosion. It just determines what you get through a fractal landscape generation seed, and a sub-algorithm goes "biome 1, biome 2" etc based on distance from sea-level. An algorithm can create a cave, it can't create "ruins" that were once an ancient city built by an intelligent race. Like V1.0 can pretty much go "What the hell is Allag?" because there is nothing in the terrain that suggests it ever existed.