Brian, I wholeheartedly agree. I too have been doing this my whole career and to me it doesn’t seem like anything special. Since I’m a freelancer, I’ve had no choice but to operate this way, but there are still plenty of designers who don’t. Just because we’ve been doing this for long time, doesn't mean it’s not a valuable hybrid combination. The hybrid nature of those skills is precisely why it’s valuable — because it allows us to make connections and problem-solve across disciplines and modes of thinking.
Product Designer is the best term for it, as you say, but I’ve intentionally avoided using that industry terminology. Many people, even in the design industry, don’t understand what it means or they use it inappropriately. My intent with this article was to describe the skills and qualities that make product designers so valuable, rather than just saying “all designers should be product designers”.