Miasma 2 was taken out originally because it was significantly weaker and didn't serve much purpose, even in large aoe pulls.

The upgrade wasn't about making up for Maisma 2, it was for making up for the loss of Bio 1.

With Bane gutted, Scholar AOE was significantly reduced. That's why they received Miasma 2 back and Summoner didn't, who still have painflare, Deathflare, and Bahamoot.