Don't get me wrong I love javascript, but I do believe obtrusive interface changes (like this one) should be made only on an opt-in basis. However it has been my experience that most of commons disagrees.
No, it would be wrong to imply that "most of commons thinks 'obtrusive interface changes' should be shoved down everyones throat". What kind of monsters do you think those commoners are? ;-)
The key mistake is reducing the new upload form to one single adjective: "obtrusive" (that makes my stomach cramp up).
The new upload form was not invented to torture people, it was invented to guide newbies (who will certainly not know how to opt-in anywhere!) through the upload process and make them provide the necessary information that had been omitted so often in a structured way (which burdened commons with lots of cleanup and avoidable deletions).
The basic assumption was that the pro's (like you (no I'm not being ironic here)) will certainly know how to opt-out.