... and we tried so hard to hide the feature :-)
Seriously, we disabled it (or so we thought) because we somehow decided the feature was not important in a script editor and chose not to support it. But as you can see the editor core certainly supports block copy.
So for now, just go ahead and use it. And if you want full support for it, try to convince us that this is a good idea by describing what you would use it for.
XLnow - the makers of OnScript