I've never noticed my upper arms getting any extra overheated but when I think about it a sleeveless jersey is probably what should be standard wear in the summer. Just a styling issue I guess.
The main reason I won't get one is because in 1987 I got an airborne tattoo on my shoulder when I went into the military. But in the 90's tattoos became mainstream with the millennial's and I didn't want mine anymore. Now everyone, even chicks, have them and when something turns mainstream is stops being cool to me. I think 99% of them look hideous. So I don't like anyone seeing mine.