Kralljin
I don't know what sort of Wotlk you've played, but i'd argue that in comparison to any recent WoW expansion, Wotlk is downright hardcore.
No LFR.
Catchup only awards gear the lowest Ilvl from the previous tier, meaning you still have to work through the previous tier rather than just jump into the current one.
If you don't raid, you can basically stop playing after farming heroics because the game is effectively over for you.
I really think that a lot of those casual players which believe WoW is nowadays intended for the "Hardcore audience" have a very skewed image of WoW that seems to be like:
"I don't like WoW anymore and i am casual, since casuals and hardcore players are opposed to each other, it means they design the game around hardcore players!".
The simple reality is just that WoW no longer has a real target audience, the game is utterly torn between catering to pseudo E-Sport, entertaining people that have only very limited time available while wanting to see every piece content and also still humoring the idea that it's some sort of RPG.
Everything must somehow work for everybody and thus ends up being a at best neutral experience for everyone because nobody gets the feeling anymore that any content is actually made for them.
That is the real issue, blindly pointing at some audience and saying "They're designing the game around those!" is just a half truth.