But you aren't vaccinating for the sake of the vaccine, you are vaccinating for the sake of the sheep
Unless you can guarantee for example you sheep will never have contact with soil (unlikely) then they will be in contact with clostridial disease. They won't necessarily get sick, but if they do you are very unlikely to save them. You are also boosting immunity for the unborn lambs with the vax.
I am not a fan of going for the needle at every opportunity, but we must IMO safeguard our flocks against diseases brought about by asking them to live in an unnatural environment. As the ovine kingdom goes, fences and lush grazing are NOT a natural habitat nor are lambing sheds and gathering pens. If you can graze your sheep on the side of the mountain and move them up and down as the seasons flow, and keep them 1 per 10 acres then I might concede they are unlikely to get sick
Edited to add, the above is only my opinion, not saying you are wrong TheCaptain

just, I don't agree with you

but no offence meant at all