Backdrop really ought to have, or be able to have, placeholders for admin form inputs. More and more designers hide form labels and rely on placeholders to provide information in a clean manner.
Perhaps the easiest place to visual this working is on the User registration/login and password forms. Here's an example:
Whilst it's feasible to add placeholders per input field and form through your theme template.php file, surely we should be taking full advantage of HTML5's features and have this in core for all admin forms?

Recent comments
Thank you, this is a very useful workaround for preparing a clean import list. One concern remains, however: if Simplenews 1.x-1.2.3 still treats blocked user accounts as invalid...
Re-enable Simplenews newsletter subscriptions that had been erroneously disabled
@Amilenkov, I have an idea for your use case where you want to avoid re-subscribing people who have explicitly opted out: Build a view of simplenews subscriptions, and filter by Status (...
Re-enable Simplenews newsletter subscriptions that had been erroneously disabled
"modules to help someone monetise their own website"
How to monetize a Backdrop site