There are other problems besides just being inefficient. In a world where energy is cheap and abundant, you still have to deal with leaks (hydrogen is small, so tends to escape everything over relatively small periods of time) and embrittlement (again, hydrogen is small, so it tends to fuse into other materials and destroy them).

I don't know if these limitations are fundamental, or if we'll eventually come across some breakthroughs that make them economical to deal with, but it's something we've struggled with for a very long time so far.