If it was like it was in the linked article it wouldn't be that bad, "Louvre," is harder to guess than "Louvre", specially if the way to check the password is not automated and there is a limit of tries before triggering some alert.
But odds are high that the password was that way to easily tell the intended users of the system what it was, in a not secure way. And that adds another dimension to the insecurity of it.
I'd guess the rationale went something like "why are we protecting a camera system to a public museum, where anyone can see whatever is there by walking in"?
Of course, this also means we don't need Lester Crest to help us find out the vault contents (so no need to hack the security guard's phone for the wifi password either).
But odds are high that the password was that way to easily tell the intended users of the system what it was, in a not secure way. And that adds another dimension to the insecurity of it.