I shaved my legs in middle school and high school. I wanted to pass as a girl. I did it to avoid being teased.
I stopped shaving my legs... a couple months ago, I think. I stopped shaving under my arms like a week ago, as an experiment. To see where it goes. If it isn't to my satisfaction, I'll start shaving under my arms again. It's irritating right now, the pokey hairs, but I'll give it time to grow out.
When I'm on T, I will also do the same thing. Experiment with the under arms, see if I like it. If I don't, I'll shave 'em. If I don't like having a hairy torso, I might try waxing and see if I like a hairless torso. After comparison, I'll make an educated decision. If I get a lot of hair on my back I'll probably do something about that. It's the one place that hair creeps me out.
I used to also always shave the bikini area. Just like my under arms, I stopped, to experiment. I don't like how it looks, though. I hope with T I'll have a bit more of a trail so i looks more even.