Why are they called spacesuits?

Suits provide little protection from the elements (or lack thereof).

I always thought it was strange how, whatever adventure or fight they were involved in, the Men from Uncle were always adorned in suits.

Coats are what you wear when you want thermal protection from the wind and rain and snow.

And they go over whatever suits you might be wearing, saving time when there is a depressurisation.

So why aren't they wearing spacecoats?