Hydrogen is easier to store than electricity, and you can produce it at times where electricity price is zero or negative (very sunny days at photovoltaic plants, very windy days at wind turbine plants, 3am at nuclear plants). Processes more efficient than electrolysis do exist.
I suppose safe storage and transportation of hydrogen is a major cost, though. Hydrogen gets absorbed into metals, because their crystalline lattices act like sponges for molecules this small. Worse yet, hydrogen can seep through things that work as impenetrable solids for other gases. And hydrogen flame is all but invisible (most radiation is infrared, nearly no visible light).
