Interesting replies...I’ve always had it on since it was introduced. I had it on my launch day Ipad Pro 9.7, then my 10.5Pro, and then my 11pro (‘18).
I always found Apple displays too cold and bluish without it. I have a Pixel Slate which doesn’t have TT, but it has a much warmer balanced screen, so I don’t really miss it there.
But I can understand, and I used to do this before but I stopped out of laziness, that when playing movies or Netflix, that turning it off would be truer to the colour the film was mastered with.
Good question OP