XForms 1.1: Why is output/mediatype text content not allowed?

 Here's the spec text for output/mediatype element:

 8.1.5.1 The mediatype Element (for output)

 Binding attributes on author-optional element mediatype specify the location in the instance of the string that indicates the desired media type rendition for the parent output. If the binding attributes are not used, the value attribute must be used instead to specify the desired media type rendition.

Why does it not allow  text content?

  <output ref="foo"><mediatype>image/*</mediatype></output>

It's hard justify this restriction because it's different from other SNB elements with value, which  do  support  inline content.  Removing this restriction would allow for more re-use of types in the schemas, and better author familiarity with our rules.  

Leigh,