Yes, I edited your post slightly to remove the unnecessary tone. No offense
Sorry that these changes were not noted in the 2.8 release. However, with the significant changes that WERE noted, particularly in group registrations, you have to assume that there will be TMPL changes.
Will there also be TMPL changes in the future. You can bet on it. Otherwise, we'd never make any new features or improvements. To expect there to never be TMPL changes is unrealistic.
In particular, the group registration process in 2.8 is totally overhauled... and much improved by the way... and yes, it required TMPL changes. We do not apologize for such changes, but yes, it should have been made more obvious to expect such modifications.
Regardless of the extension, you should always check any files that you have made tmpl mods to. Personally, I do this when I upgrade various extensions on sites I manage, because I OFTEN find changes to these files in a wide array of other components and modules.
Anyway, note taken and shared with everyone else... 2.8 includes some TMPL changes
Thanks!