Yes, umm No, umm maybe?
Millions of players, millions of opinions. I think if you rephrased the question, should WoW be fun and challenging, more may say yes.
Challenging is different things to different people. A normal dungeon, or LFR may be more than enough challenge for many. Heroic dungeons and Normal/Heroic raiding others. And up through Mythic. Where the line for me is drawn is different than for others. The problem I have is introducing competition. I use to think that it was wrong to steer players into competing. Because it tends to exclude people from seeing certain things or earning rewards by locking them behind the hardest toughest content their is, and let’s add a timer to it also. But that mentality plays into the everyone deserves a trophy line of thinking. And I have to admit. You can’t make a distinction for one thing but not others.
I think the underlying problem is not who is doing what form of content, but when people berate others for not doing what they find easy. If everyone stepped back and just encouraged people to play the game, play it how ever they felt like, not expecting them to be able to do things they have never done perfectly the first time, then the gaming world might be a better place.
No tank or healer or DPS just steps into a Mythic +10 for the first time and just facerolls content. Many people have to learn by doing. Some may watch a video and have it make sense, others may find it confusing. We all learn at our own pace. Encouraging people to learn in what ever way they can, leads to improved playing.