What you suggest is a work-around. It works around the fact that the FPS is a poorly designed pain in the butt. Your suggestion, that someone just go out and purchase ANOTHER product and strap it to their body all day, just to easily access their cell phone, is ridiculous. Now, YOU may use that set-up. You may like it. However; that doesn’t mean it’s a good suggestion. Not everyone wants a smartwatch on all day, buzzing you and annoying you. Plenty of people already wear nice watches, Omega, Rolex, Panerai, etc. Why would they take those off for a crap gadget, just to access their phone? See, just because there IS a solution doesn’t mean it’s a GOOD solution.
Oh yeah, it's also not secure. Maybe that doesn't matter to you. It matters to me, it matters to my employer, and it matters to my clients.