I’m guessing the devs chose the current timescale so that a game starting in 1850 and extending to 2000 can be finished in a reasonable amount of time, not take weeks and weeks of playing.
However, I now normally start in 1900 or 1950 and an optional longer timescale would work out well there. It’s kind of like the Civilization series — you can start in a more modern era and set the game pace to a slower speed. Various game factors are adjusted to keep things balanced.
On the other hand, there are times when I’m just letting the game run while waiting for a particular engine or something to be invented, and an 8x fast forward speed would be handy then.