Sometimes you need to access production with a special user role to see what this role can see. Or to understand an error that happens on production but nowhere else. ... I think there are a lot of valid reasons why you want to do this.
In this case, I don't like the idea of using a real users account. That's where the test users enter the stage and they can be very helpful.
If you don't want them to stay in your system, you could only create them on demand and remove them when your work is done.