[css3-background] Default shadow color

The color element of a box shadow is optional [1]:

	"...omitted colors are a UA-chosen color."

Is there are reason not to make the shadow color currentColor as opposed to 'a UA-chosen color' ? This would also apply to text-shadow and make this clearly testable, at least.

[1] http://dev.w3.org/csswg/css3-background/#the-box-shadow