Why doesn't xsl:copy have a select attribute?

It could work like <xsl:for-each> in that it requires an XPath expression
that returns a node-set, and, like <xsl:value-of>, it could ignore all but
the first node in that node-set.

This seems much better than having to change the current node all the time
by applying a template or using <xsl:for-each> (semantically misleading).

Is there any reason why <xsl:copy> shouldn't have a select attribute?

Thanks,
Evan Lenz