EDIT: Updated with 8.3 News. So far no changes to the original rep requirements on the original essences.
The Essence Grind on Alts is Worse than Forced Pathfinder Part 2
Pathfinder part 2 requires you to do all of Nazjatar and Mechagon dailies for rep or follower xp to obtain essences. You need to do this set of content on repeat for about 4-6 weeks on top of all the other gearing systems in wow that include alot of rng and time gates. Pathfinder Part 2 basically tells you to get revered on all of these reps. For essences they you need revered then exalted. Never before 8.2 did Blizzard force you to do a rep grind in order to have character progression. It was always an option never a requirement.
Then add on top of that what you need for the other essences from pvp kills. I respect the Mechagon dungeon essence as that is on a weekly reset, same thing with islands, same thing with mythic pluses and raiding. What I dislike is the lack of a catchup mechanic for the rep, pvp and daily quest grinds. I would appreciate a catchup mechanic for the others as well.