You are right, in the end all of life is based on pushing electrons around -- because Albert Szent-Györgyi's "Life is nothing but an electron looking for a place to rest" stays just as true if you replace "life" with "chemistry": all of chemistry is "just" about electric potential.
It is "just" that life goes on to do something interesting with it.
This was something we knew though -- Albert Szent-Györgyi said the above sentence some time in the 1930s. So it is "just" biochemistry. I keep using scare quotes on “just”, because you can’t really use that word with any of the processes of life in earnest: pretty much all of it is amazing. Just look at photosynthesis, the other electron chain transport example -- moving electrons from one level to another with light photons while pumping protons to create a proton gradient, then using the exquisite nanomachinery of the ATP Synthase to capture the energy in ATP. "Chemistry" doesn't really do this apparatus justice, it is evolved, electromechanical nanomachinery. Truly the stuff of science fiction, if it wasn't the stuff that makes all of us alive. (There are many processes inside the cell that are truly mind-boggling, even more so than ATP phosphorylation -- for example the whole protein synthesis, starting with RNA transcription, over the ribosomes, ending with the chaperones -- but that is something, maybe, for another article.)
What we didn't know, though, is that microorganisms can pass the electrons around between each other like a currency, to such a degree that different kinds of bacteria in biofilms will keep each other alive by passing electrons to each other -- and to a point where you can literally connect electrodes to both sides of the biofilm and let the bacteria live on nothing but air and electricity. Or feed them, and get electricity out, like a battery (this is what a microbial fuel cell is, and people have been looking into that ever since that "little" discovery at the Oneida lake.). To emphasize how much of a discovery that was: we have an official new group of autotrophs now (organisms that can produce their own food) -- "electroautotrophs", designating microorganisms that can live on electricity. We (humans) have literally called a whole branch of the tree of life “electric life”. I think that should count for something :-)
In a way "it should have been obvious", because, as you say, both mitochondria and chloroplasts likely used to be separate microorganisms, and for them, electron and proton transports through the membrane are the whole point of their existence. But of course, everything is obvious in hindsight.
