We actually had an "disagreement" with our "old" vet because of this very issue. It wasn't the reason we stopped, but just added another issue.
We specifically requested no lepto and the vet "in a very non-chalant" manner dismissed our concerns. We actually had to basically say, that if we were going to continue the relationship then "NO LEPTO".
We have 5 and none of ours get lepto anymore.
Piper (at the time our smallest) always got sick after her vaccinations. Two years ago, when we learned of the issues with lepto, we had them stop and luckily she hasn't had any issues at any vaccination since.
While this doesn't mean that they will NEVER have adverse reactions, it is at least one more step to helping to prevent them.
Just as Ellie May mentioned, it's a non-core vaccination.
I don't get a malaria shot, my risk of getting it is extremely low in Indiana, so why would I get my babies shots for something that is most likely, unlikely for their environment.
Here's a link that may help you to decide.
Leptospirosis in Dogs