The Terminator franchise is one that really needs it, though. It's not gratuitous for two reasons.
First, it already revolves around time travel so its not like they're splicing it in to fix things. Sure, Trek had time travel in certain episodes and movies but the Terminator franchise is based on it. It's not out of the blue.
Second, Cameron painted them into a corner with the declaration of a judgement day date and has been painting around that corner ever since. There's really nowhere else left to go unless they move backward.
Everybody good, plenty of slaves for my robot colony?