one contributor was suggesting that the terrorist threat was a good reason for Americans not to visit Europe.

The OP referred to me, but I did not say it "was a good reason."
The risk to an individual is indeed dwarfed by everyday risks.

I merely pointed out that any country that suffers a terrorist attack also suffers a drop in visitors.
Brits have stopped visiting Tunisia and Egypt following single attacks.

The UK government advised Brits not to visit Belgium for several days last week.
Scaremongering?
UK government and security forces say an attack here is "highly likely."
Scaremongering? No. A rational assessment, but the result is that people will choose to take their families elsewhere.