The 40% (66%?) is the number that matters. Same way you wearing a helmet reduces your changes of brain damage in a motorcycle accident by 90%, yet you’re not on a motorcycle most of the time.
One should weigh the cost of the proposed intervention in time/money/other_expense against the potential benefit. The potential benefit is the total reduction in risk * the magnitude of the unwanted outcome.
40% is less relevant.
For example you see this oft-quoted stat about "statins only increase lifespan by 3 days" based off relatively short RCTs, but this doesn't capture the effect of statin use over decades, which is where we see much, much bigger gains.
It seems to me that both RR and AR are things to take into consideration and we have to be mindful of the shortcomings of each.