But that's exactly what changes it. Adjusting the difficulty of a game can make it an entirely different game, even if you keep the core elements the way they are. Take Demon Souls as an example, it would be quite generic and pretty average if it was a forgiving game, the difficulty is what sets it apart. You can see the same reactions in other games aswell, PoE used to be a very unforgiving game, now it's very easy as long as you don't feel yolo. That being said, WoW did add a few good features when it comes to the PvE side of things. That the raid size is more dynamic is a great thing and I never really heard anything bad in this regard from anyone I personally know, when it comes to the PvE side of things. PvP is what people despise, for a good reason. Every comfort feature WoW added was at the cost of the games depth, leveling skills was annoying while you leveled up for sure, but it was an element of depth for PvE and PvP which people actively used. Dungeons and raid finder made the game a lot more comfortable also, but did you level any character? It was at the cost of the world feeling empty and dead, I personally didn't encounter anyone once for literally 4 level.
TL:DR; Comfort features as nice, but it's about the balance, since every comfort features comes at a price. WoW simply over did it in the past years. Some of the new features aren't even that interesting, like player housing existed in a lot of MMO's already with some even doing it better and the pet system was a straight rip from dragon quest.