2010/5/18 Ilmari Karonen nospam@vyznev.net:
The problem here is Wikimedia sites. If you leave the debug mode off and serve fully minified scripts on WMF sites, the hundreds if not thousands of people who develop user/site scripts for them will have a very hard time debugging anything that involves interactions with the minified code. If you turn debug mode on permanently, you lose most of the benefit of having a minifier to begin with (Wikimedia being the single biggest user of MediaWiki).
I have recently configured test.wikipedia.org to pull all of its JS/CSS locally rather than from bits.wikimedia.org (for better isolation) and serve all UsabilityInitiative JS/CSS in raw, multi-file format (rather than combined and minified, which we use on 'real' wikis); all of this is to aid testing. The script loader could also be configured to serve its JS minified on normal wikis and unminified on testwiki.
Roan Kattouw (Catrope)