This is currently intentional as for the "edit" log, it simply shows a list of fields that were edited. Of course, the alternative is to potentially log a whole bunch of changes via the edit thread overlay. Thoughts?
I share that personal preference.
I understand a log is just a log, and used incidentally on most sites.
But 3 months down the road when you need to review a moderator, it's important to trace back content and have it make sense. You can't remember those details especially when it's not seemingly important at the time.
Accusing a moderation who's getting away with 'that is just an assumption' leads to nothing but trouble.
The ability to point out 'it clearly states you have been changing sales threads assigned to one user to yourself at least 15 times a day' would .. resolve any potential dispute.
I've changed this to log all the known edit events separately. Unhandled changes still go in the general "thread edit" log. Note that we only show/log the old value for the field (as you can trace back from the current value).