I guess because I'm scared that I won't know if baby has a high temperature, and it's a way to be reassured that she doesn't.

I have the impression that they are a useful piece of equipment to have, though not one our mothers and grandmothers relied on.

Maybe I should rephrase my question to go more like :

Did you get a thermometer?
Did you use it?
What kind do you think is best to get?