It's "easy enough" to write a lot of scripts, but we're starting to accumulate a number of such scripts. I'm not trying to be negative, and I understand why the $key/$elt_id reference structure imposes this constraint. But many of my writers are nontechnical; if I switch from the WYSIWYG view to the XML view in Oxygen, you'd think I'm giving them a sneak peek into The Matrix! And as the champion of our move to DITA, I'm responsible for all automation to hide these sorts of details from them.
In my opinion, having keys map to files is handy, but requiring keys for subtopics in those files is a bit limiting. It would be nice to have the option to use a $key/$subtopic_id reference structure as well.
Enough wishful thinking. It's <glossentry> hrefs for now. Back to work!