[CSS21] Scaling of replaced elements

Currently, the spec [1] states that, for replaced elements with an  
intrinsic ratio, it is an optional requirement that a UA scale the  
element.

I'd like to propose that the current spec is further clarified so that  
scaling a replaced element is recommended (SHOULD), as opposed to just  
optional (MAY).

Leaving scaling as optional could (although unlikely) result in a  
vendor implementing behavior that differs from currently consistent  
implementations in other browsers - FF, Safari, IE, and Opera all  
scale replaced elements (which have an intrinsic ratio) in this way.  
More so, authors have become reliant on the behavior found in these  
existing implementations, and to allow the possibility of a differing  
implementation would no doubt affect interoperability.

*ASIDE*
Surely, the aforementioned prose should be repeated in http://www.w3.org/TR/CSS21/visudet.html#the-height-property 
  too?

[1] http://www.w3.org/TR/CSS21/visudet.html#the-width-property