Copyright Lines - What do you think?

[Caddyman]

It is their right to add a linkback for them. They put in the time and effort to put the mod out, so it is up to them...

That said, of course, most would agree if you are releasing a tiny template tweak or something very simple a backlink shouldn't be needed and if you are releasing a big complex super helpful mod that it is....but inevitably it is up to the author if he/she wants one or not.