The last time Hydaelyn gave us an aether blade she nearly drained herself of all of her power. The next time was made possible through an ancient aether syphoning/manupulating stone drawing a crap ton of aether from all around Mor Dhona and we still needed more aether to fuel it, resulting in a character death. And the third time required drawing aether from an object that had been accumulating aether for thousands of years.

Popping an aether blade whenever you happen to need it isn't really a thing.