Why the BLM nerf?

[Lunavi]

And you are forgetting the most IMPORTANT part. One that is not so obvious if you do not look closely. That they made Umbral end when you cast a Fire spell instand of when it lands. This might not sound like a big deal to someone who do not play BLM, but it really is. Not only because it takes away double flare, but because it severely messes up our rotation. If I do not wait like 0.3 sec after a thunder 2 I might not get fully charged and sometimes it starts to charge directly in a way that feels very random and awkward. It makes it impossible to predict what to do to keep rotation 100% optimal.

[Sylari]

That they made Umbral end when you cast a Fire spell instand of when it lands.

Actually it appears worse than that, UI ends a moment or two before the cast finishes, so it's very possible that if you have to move mid cast you'll end up with no stacks at all.