It would be nice if XQuery 3.0 provided a way to perform a shallow copy of the context node while preserving its namespace context (like <xsl:copy> in XSLT).

In the current draft, the only way to do that would be to write the following:

$el !
element {node-name(.)} {
  for $prefix in in-scope-prefixes(.)
  let $uri := namespace-uri-for-prefix($prefix, .)
  return namespace {$prefix} {$uri},
  "new-value"
}

whereas in XSLT, you'd just write:

<xsl:copy>new-value</xsl:copy>

It would be nice if XQuery 3.0 provided a simpler way to do this, e.g., through a shallow copy constructor, using syntax that looks something like this:

copy {...}

So the above example could be written like this instead:

$el ! copy { "new-value" }