That sounds very complicated to implement for something like a circle or irregular shape... now that you can add multiple drop shadows, maybe add a drop shadow at n-degrees with 100% opacity and offset by # of pixels you want the stroke to be wide? You could do this with multiple drop shadows in different directions or colors, too.
I understand, but it could have some interesting results for irregular shapes, but it could still work.
I find that for web design, Ioften find I just need to add a border to the top or bottom of a graphic (not left or right) and stroke is the closest thing. It's useful as it would allow the designer to resize an element without having to create and move other layers. I still think this is a useful suggestion to explore.