I think the collision thing you speak of would require a lot of work. Probably the fastest way to check the collisions would be to render the vector graphic onto a texture then pixel check that. Otherwise I guess they would have to write some sort of equation solving collision engine (unless dx already has some sort of library built in for this, which I'm guessing is more than plausible.).
Anyways, I'm all for some sort of geometric drawing capability, but I believe it's too much work right now to expect anything useable in the near future. What I would really like to see is polygonal drawing capabilities with the canvas. Speaking of canvas, there's a hell of a lot of bugs with it... Guess I better go report them.