I’m on the West Coast (California), and granted in a rural area. But my vet DOES recommend rabies vaccine, and the big vet clinics in the area do too. Bats are a risk - a SMALL risk, but a risk. A healthy bat will not bite a horse, but a rabid bat is not a healthy bat. And we DO have rabid bats, and skunks!
We are not allowed to do our own rabies shots in CA, it must be done by a vet, so cost is about $40 - once annually. I consider it a small cost. If I had a horse who had a bad reaction, I might skip it, but so far, the worst reaction I’ve had is minor tenderness, and for that horse, a dose of banamine with the vaccine (yes, it adds to the cost, but worth it once/year) makes all the difference.
I would not skip it, personally, but again, I’m in a rural area - bats and skunks are very common out here. As are feral cats, coyotes, and other animals that could interact with a bat or skunk.