You have to do both nazj and mecha to unlock zones, even if not the complete chain.
Nazj is also mandatory to unlock the chamber of heart, so I don't know what are you talking about.
About essences you have to unlock them ( even if you can wait and unlock them through visions ),and about cloak, you have to do them, unless you can't manage the corruption from items ( if lvl 15 would have been the cap it would have been barely ok, but surprise, past lvl 15 is +3 corruption every week, which is mandatory, for either main and alt ).
Your second point is totally nonsense.
You are somehow glad that they forced players not to have alternative ( it is right they have to grind as the main! ). I see no purpose in this.
But still better than your last point
No even sure if you were genuinely honest there.nd lately I genuinely hope even switching specs should be expensive as fuck