XSLT 2.0 Processor = XSLT Processor + W3 XML Schema Validator

["Roger L. Costello" <costello@mitre.org>]

XSLT 2.0 has incorporated validating functionality.  For example, you
can have this literal element in your stylesheet:

   <Cellphone validation="strict">...</Cellphone>

The validation="strict" attribute instructs the XSLT Processor to locate
the corresponding Cellphone element declaration in an XML Schema and
validate the literal Cellphone element and its children against the XML
Schema element declaration.

I am wondering if mixing styling with validation is a good idea?  Here
is my list of pros and cons:

1. Increases complexity: it increases the complexity of stylesheets
since now you have transformation concerns as well as validation
concerns.

2. Separation of concerns: isn't is good to keep concerns separate?

3. Exclusive party: note that validation is against a W3 XML Schema. 
RelaxNG, Schematron, etc are excluded from this party.

4. Powerful: on the plus side, this can bring a lot of interesting new
capabilities to XSLT.  I could even see it eliminating the need for a
Schema validator.

In my list there are more cons than pros.  But, I am sure this is not a
complete list.

What do you see to be the pros and cons of this new validation
capability in XSLT?  /Roger