Fair point, same here (I was born in 1967), however fossil fuels are so effective and adequate as energy sources, as long as we ignored/neglected their dubious effect on the climate, that there was no real attempt to explore other ways.
> Storage and transport are incredibly expensive and technically difficult
For the "gridpower backup" application there is no transport needed, and storage doesn't have to be compact nor mobile (those are a major challenge for hydrogen in transportation).
> dreadful energy density
This is not a show-stopper for the "gridpower backup" application. For huge volumes or very long-term (not sure this will be necessary) it may be stored in salt caverns ( https://en.wikipedia.org/wiki/Hydrogen_storage#Underground_h... )
> potent green house gas effects > dangerous
Granted, however we are used to store huge volumes of dangerous materials, some gaseous at ambiant pressure/temp (methane...), even into salt caverns, albeit when we began to do so (in the 1950's) it was quite a challenge.
> Roundtrip efficiency (electricity to H to electricity) is abysmal
Various new ways to obtain H2 from electricity offer impressive yield in realistic conditions (check SOECs), and other advances are promising ( https://liten.cea.fr/cea-tech/liten/english/Pages/Strategic-... ).
> green methane makes a lot more sense
As does ammonia, in some contexts. There is no one-size-fits-all here!