Mana pearl grind is irrelevant, it's not 8.2. Let alone the fact that you could actually grind them and not be hardcapped, unlike essences.
I disagree - the morale effects of mana peal and essence grind on alts has pretty much eliminated all but the most hardcore in my guild from maintaining them. I have plenty of 120 alts - all of them undergeared, with no essences. Sure I could spend 3hours doing the cloak quest, then chain-run m0s, then slam my dick with a hammer, oh I mean get blood of the enemy rank3 on them, then spend a hundred hours pugging m+ .. but I haven't played them for months, and there's noone to do alt-runs with - why bother ?