I mean, honestly having the pause, or some other conformation that work was completed is useful. If you ever had a system 'fail successfully', finishing to fast does become a concern.
Having meaningful output is useful, artificial pauzes like this are only for dramatic effect. I rather have a linear, timestamped log, so I can confirm my suspicions, than a progress bar with artificial delays, that suggest progress.
But that's the techy point of view. Most non-techies will probably prefer feel over functionality. I think most people do. If something is instant, it feels too good to be true. If something takes ages, you'll get bored or frustrated. While things that take a proportional amount of time feel satisfying.
