I have a theory about why electricity is assur on Shabbos,
despite its use not violating any melachos. I'm not a halchic expert by any
stretch, not am I a lighting historian, so take my speculation for what it's
worth, but I think the evidence speaks for itself.
The transition from gas lighting to electric lighting wasn't
sharp or sudden. Electric lighting was adopted slowly, there was a period when both gas and electric lights were in use, and the first electric
fixtures were nearly identical to gas fixtures.
One of these is a gas fixture, the other is electric. Can you tell which is which?*
The controls, as well, were very similar.
After all, people were more likely to buy things that looked familiar. The knobs at right were early electric switches, reminiscent of the knobs one would use to adjust the amount of gas flow to gas light fixtures.
These removable keys were also used to adjust the gas flow to gas light fixtures. If you look closely at the vintage electric lamp on the right, you can see that the switch is shaped just like the control key for a gas fixture.
I think that electricity is assur on Shabbos simply because lighting was the first home use of electricity, the electric fixtures replaced nearly-identical gas fixtures that actually were assur to use on Shabbos, and people mistakenly thought that they were the same thing. Decades later, when electicity was common and people realized it's not fire, there was a scrambling to justify the extant practice, and so we got the specious idea that closing a switch is maka b'patish (which would also make opening a faucet or closing a gate assur) and then later RSZA's more honest assessment that there's no halchic reason for electricity to be assur on Shabbos, but it is becuase everyone accepts that it is.
*The top one is an early electric fixture, the bottom one is a gas fixture.
