Nah, you can’t beat the power density of hydraulics and never will unless room temp superconductors become a thing.
Big Dog from Boston Dynamic was hydraulic.
Going that size or bigger, hydraulics is a must.
The reason you don’t see it is hydraulics is a completely different ball game.
Controls researchers stick with small and electronic, because that’s what they know.
It’s very rare to find a controls engineer that understands hydraulics.
And the hydraulics experts out there, don’t have the background for sophisticated control theory.
I’m not sure why you say that. They are not.