Not every area needs to be a place to fear, and I don't know... Classic players of today seem pretty secure in the way they handle world mobs.
Shitty tuning =/= design to keep players on their toes. We've seen areas with a more punishing design in mind added just fine through iterations past Classic. Most recent being Suramar Areas, Isle of the Watchers, certain Elite areas on Argus (the elites are not always up so when they are, people run in and get 1-shot if not careful).
I for one hope they'll utilize M+ affixes to the world to make it TRULY challenging, as an optional path.