Save lines of code != get work done quicker. What might appear as a paradox should be obvious: we spend more time debugging, modifying, expanding and organizing than writing.
IMO, imperative programming cleanly maps out to the real world.
More so does CUDA with a random number generator. You can't get more precise than quantum (yet).
Truth is it's so much more easier to think imperative.
That's like saying it's easier for a Chinese to speak Mandarin than for a French.
So, Is functional programming really worth it?
To use, it depends. To learn, yes. One can't learn too much in life.