Now, to the topic: The RPG formerly known as World of Warcraft (aka Wow).
WoW used to be a DnD like game, with various elements such as reagents for spells to the roleplaying elements of playing a race and/or class. However, it's sad when you think the tabletop rpg version of wow has more rpg elements to it than the MMO version does. Why is that exactly? There are many answers and not all of them are right, mostly due to the fact a wide number of answers are based on opinion.
These are my answers based on my opinions, so I don't speak for all of gamerdom or WoW players in general. Lets discuss reasons why WoW the MMO isn't much of an RPG, just to keep things simple and keep people from reading a wall of text.
1) Simplification: This is probably the first and foremost reason I think a lot of people might agree on, so what is that you may ask? WoW now longer has or uses the following that are essential rpg elements:
*Reagents for spells, i.e. materials for spells to work.
*Spell ranks, meaning a fire ball just scales in damage
*Quests to obtain abilities in WoW for your class, such as shamans doing quests to learn and control totems, druids learning and controlling an animal form, etc etc.
*Weapon skills, you no longer have to train to use a weapon effectively.
Now simplification occurs in other ways, not just in regards to remove or streamlining gameplay. Another way that Blizzard simplifies WoW, is "core classes". What are those? They're all the basic classes you'd find in most rpgs, but they have specialties for those classes crammed into one class. So a Rogue in the MMO in WoW has classes like: thief, assassin and duelist for example, combined into one "core class"
2) Nerfing & Buffing: Nerfing can be defined as the reduction of stats (etc) of gear, spells, classes, etc etc. Obviously buffing is the opposite of that, so how does this make WoW less of an RPG? Probably due to the fact that they can't get it right, and most of the time screw up the game accidentally while trying to fix it. Say you're a PVP kind of player, well...someone on the PVE side has used what should be a pvp only move in a pve setting and is doing more damage (for example) than they should. Blizzard eventually gets around to hearing more and more reports about people doing the same thing, so they "nerf" the ability to make it no longer viable for that pve situation...and be extension not worth using in pvp.
Blizzard cannot fully balance all the classes, so they're almost constantly buffing and nerfing classes. And the imbalanced nature of the WoW MMO leads to unintentional bugs and glitches, that plague pve and pvp situations. I am no game designer, not even a computer programmer...and even I admit that progamming for the WoW MMO is hard. They really are trying to "fix" the imbalce issue between classes, but they are failing big time. Case in point, Death Knights. DKs are the first "Hero Class" in the WoW MMO history, they are the last I think. When DKs hit the scene, they were considered overpowered, and many people felt the threw an already unbalanced game into chaos.
Remember, until DKs came along players only had "core classes". Simplified classes combined into one...so when a Hero Class is thrown into the mix, it throws their hold world into turmoil. DKs are a core class too, but a more powerful version of that. So naturally, Blizzard eventually nerfed them right into the ground. I know many people will probably disagree with me, but this class was way more powerful than any other in the game for a reason. But now, it's no different than the other core classes.
3) Limitations in Factions, Races and Classes: You only get two factions in the WoW MMO to play a race/class combo from. You're either the Alliance, which was founded by Humans (mostly) or the Horde which follows the banner of the Orcs. There are so many "neutral" and just plain hostile factions in the MMO you'd have to have all the expansions just to see them all...if that. But Blizzard won't let you play as a member of the "The Scourge" a massive undead faction ruled by the Lich King, or even demonic "Burning Legion". DKs are somewhat an exception, because you do fight on the side of the Lich King for a brief time, before forming your own Death Knight faction...which still force you to join the Horde or the Alliance.
Races are another issue, there are a number of races that have either allied or are simply a part of the two playable factions. This should mean you could have a wide range of races in such cases to play as right? Nope, and here is why. Blizzard gives 6 on each side to play as, and a neutral 7th race you can play as that will still have to join either horde or the alliance. There are variations of most races that are allied with the factions you play as, but you can't play as one of them. Take a dwarf for example, as of right now...there are 3 main types of dwarves that are allied or out right a part of the Alliance. But you get no choice to play as one of them, you play what is known as a Bronzebeard Dwarf, that's it.
Before one of the expansions, the Dark Iron Dwarves had more or less okay relations with the Horde, and was rumored to maybe join it in the future. However, Blizzard killed that idea with the excuse that having both factions have dwarves would cause confusion and would give the factions as much diversity as they should have. That was a semi-legitimate reason, until the neutral race of Pandaren came into the game. Pandaren can join either the alliance or the horde, and they all look relatively the same. Which means that whole reason for dark iron dwarves that Blizzard gave was either a lie, or they wanted to really test out that theory by adding a truly neutral race that both factions can play as.
The playable undead race you play as is called The Forsaken, and they are pretty diversified in regards to any other race in the game...save for the scourge. But, you can only play as an undead human, despite the fact they have undead versions of half the playable races on the horde side and a few from the alliance side working with them as NPCs.
Classes...that was pretty much explained in the simplification part, but there are classes in the game that characters can't play as. Many of which I'd like to play as, but can't due to the fact they don't have a core class counterpart or something yet...lame I know, but it's the game Blizzard wants more or less. Also, there are rare exception in the game's lore that allow npcs to be a race and class that players can't. There really isn't any more that I can say about this subject of classes that I haven't already said.
While theses aren't all the reasons, they are the 3 most highly talked about topics I've seen. Remember, I don't speak for or on behalf of any WoW MMO player...these are all my opinions and observations I've made in my years of playing. While I do wish they'd add more of the rpg elements they took away, add more in general, I admit that this is Blizzard's game...not mine. So they can do what they want, even if it is or not based on the opinions of their game's fanbase.
Hope this wasn't a huge wall of text, until next time..