Why is all new content such a cakewalk?

[ValCat]

(...)
How are they shifting it back, and what's the difference between old hard modes, old Mythic, and new Mythic? How are they focusing on raids?

Okay, I don't buy into the notion of ranking games universally. Different things in different games just fit preferences more or less.

For the dungeons:
Pre-Draenor, you wouldn't have had that triplet of dungeon difficulties. You had normals and heroic dungeons. I, personally (!), liked that better.
The introduction of mythic dungeons was meant to reflect higher raid difficulty in content for smaller groups. Mythic + deepens that system (it is a progression system where the dungeons get increasingly more difficult). So yes, more effort went into that content since Draenor.
And WoW's always put emphasis on their raids, that is nothing new. The focus of the game is much more on the endgame, than it is here.

WoW had become increasingly difficult to play with alts (this would take a lot of time to explain) and you need to do that in contrast to ff14 to experience different classes.

The shifts I have heard about, are small things, really. Toys you can use for RP (like skybox changes, or that just stay a bit), the one group that stuck with WoW forever and was never catered to. Or the halfed cost to upgrade gear for alts, that I've heard about, more satisfying world exploration. More and divers overworld-content. If they'd been sure that a focus on pure progression on main characters were the werewithal, they would have stuck with that, imo.