We often default this to false, because we want admins to see failures rather than potentially mask them by doing an auto-restart. You can create a lot of junk if the process is auto-restarting frequently, potentially leading to issues like running out of disk space. If admins find that there's some known problem and they want the auto-restart workaround, then they can toggle it on.
Can you elaborate more on why you'd like it on by default? Are there specific common known failures that can cause your roles to die, or is it just to improve availability?