I would love to see a detailed change log to help when I encounter issues after upgrading from one version to the next. For concrete examples, I've come across these issues recently:
1) Files saved to %TEMP% were displayed to the end user in the 10.0 but not 10.1 when running in the gallery.
2) The cross tab in 10.1 would run with a warning if you had column heading of "p_d" and "p d" where the space in the latter item is changed to a _ and then one of them is renamed with a 2 at the end ("p_d" and "p_d2"). In 10.5 you now get a warning and an error and the workflow stops. I've attached a sample workflow.
I'm all for bugs getting fixed and the improvements not always being backwards compatible, but I struggle with some of these when I can't reference a detailed change log. For some context, I've also attached a change log from some other software I used in a previous life. Anytime that a change in coding could affect past results, there was a note in the change log to identify these changes to the end user.