Back when everybody had to get their close-ups, lol. I think it was partly because TVs were small back then, and they wanted to show off clear shots of the stars.
My favorite is how every woman they meet gets the same shot, but with that "Vaseline smeared on the lens" effect.
Devil In The Dark is still a top Trek episode for me, and I actually like the space battle in Balance Of Terror much more than the finale battle in Wrath Of Khan.
I was blown away by how good Balance of Terror was on my current rewatch. The tension, the strategizing - this is the kind of action that I find exciting.
All of the “submarine combat but in space” tricks were so good. It’s one of my favorite depictions of space combat in any TV show. Visual media rarely replies on tricky cat & mouse space fighting.