I doubt Midgardsormr took the blessing so he could use it to make his body. He's in Mor Dhona, the aetheric fountain of the world - no extra aether needed.
He removed it to test us, and stop us from draining Hydaelyn any further since she's very weak atm.

Interestingly enough, big fcob spoilers
I wonder if the primal Phoenix was created due to Hydaelyn. If she expended her energy to give Louisoix the power to transform. The prayers to the 12 were one thing, but the aether had to come from somewhere.

If she expended a lot of her power to help defeat bahamut in the calamity, then that would explain why she's been so weak since the beginning of the main story. It wasn't apparent because she wasn't exactly doing much at first, but I do believe here strength has been waning for a while - since the calamity even.

Stopping Ultima was probably the breaking point, but I doubt that it drained her that much seeing as she's the mother crystal & a mega primal.

....and I've gone off topic, sorry >_<