Maybe it's one of those not one rule can fit all kind of situations?

I typically don't wear sleeveless for work although I do like the look when the weather is warm enough. I guess I just like to be covered. However, I have noticed that senior women in sales and marketing are totally comfortable in sleeveless sheaths while women in engineering hardly ever wear it. I totally think it is appropriate if the dress goes all the way to the end of the shoulder and there are no bra straps showing.