This idea has been developed and deployed to Canvas
The bulk due date changer released 4/18/20 is wonderful, but doesn't include the option to set a due time. Let's vote up the idea to add time to the bulk due date changer!
August 2022 .. still no way to set the due times. Yes, there's a default time now, but it can only be set to the whole hour, all my classes start on the 30 minute mark and assignments are due then. Yes, I could make them due 30 minutes earlier, but that’s strange and confusing, and guaranteed to result in students submitting work late.
There has to be a bulk way to edit all my 9:30 AM due times form a previous semester to say 12:30 PM for this semester once they have been imported (dates are adjusted ok for the most part). Each assignment has two due dates/time (regular and late), say 20 assignments per semester, 40 new dates/time to be set, 3 courses, that’s a 120 time this has to be done (and without errors). Tedious and waste of time. Adjusting dates is much more complex than times, so it's odd they would do one, but not the simpler one.