Looking at the figures in that article, and taking the largest estimate of how many cases there are per year in the US, I can see why my GP has not recommended the booster to me. As a proportion of the population getting whooping cough, the number of people affected would appear to be a tiny fraction of one percent of the population. I presume it's the same here.
In short, though there is a risk, the risk is extremely small. Vaccinating pregnant women (and those who look after infants) seems like a good idea. I expect this is why the booster is recommended in the UK for those groups.
The cost for everyone over a certain age to be vaccinated would be huge. Demographically speaking, the problem is not huge.