Usefulness of (t nil) as the last sexp in (cond ...) constructs?

[Bastien]

There are many places in *.el elisp files where we have this construct

(cond (...)
      (...)
      (t nil))

My understanding is that (t nil) is useless, since the ̀t' condition 
is only tested if other conditions are `nil'.

What is the purpose of (t nil)?

Can we safely remove it?

-- 
 Bastien