I don't think this is OTT. The US has been dealing with resurgent whooping cough for longer than the UK, and this has been recommended in the US since 2005. It is called "cocooning" -- you create a cocoon of immunity around the baby. (The DTaP vaccine, which is just being introduced for pregnant women in the UK, has also been in use for pregnant women in the States for a while.)
I'm expecting a baby in March, so I've asked my obstetrician (private, here in London). He said it isn't done in the UK and he didn't really have a view. (He is also skeptical about doing the WC jab to the mother because there isn't evidence that it helps -- it's just hoped that it might help.) I'm planning to have the WC jab myself when the time comes, because there isn't any downside, and I was thinking DH should get one. I mentioned this at the GP when I got my flu jab and the nurse said it wouldn't be available for DH.
I'm taking DD (3) to the paediatrician next week so we will ask her if she has a view about this as well.
Now, I am thinking that it makes sense to get DH vaccinated privately. Particularly since there is no conclusive evidence that me getting the vaccine will protect the baby, and we know that he will be less likely to infect the new baby if he has been vaccinated. After all, he rides the Tube every day. (OTOH, he had all his jabs as a child -- we just don't know if the immunity is still good.)
So, I am struggling with the same question but don't really have an answer.
But I do know it is a complete fallacy to think you can protect a baby by just not visiting if you aren't well. Like many serious illnesses, you are contagious before you have symptoms. These diseases would not be dangerous if prevention were possible through that.
Sorry to write such an essay but it's complicated!