Using Module Errors for Deprecation Messages

I haven't brought this up in the Grease pit or the Beer parlour in order to avoid the usual rabid over-reaction, but I don't think you should be using module errors to tell people a template or module is deprecated: it's overkill, it clutters up Category:Pages with module errors, and it renders old discussions difficult to read as well as putting them in the module error category (what's the point in retroactively warning people that they should have used a different template 5 years ago, 4 years before the replacement template was created). If you want warning messages and cleanup tracking, you can do that without module errors.

But then how do we tell people not to use it?