I completly understand that you only want to work for really useful things, and not implement everything everybody thinks about.
To be exact, with my actual problem (strings containing URL, in uppercase) : i've already reviewed 335 strings in french for standard components. If i select all components, i end with 723 strings. So, i've already done nearly half of the work. But, knowing that 171 strings aren't translated, i only have 723 - 335 - 171 = 217 strings to review (less than 40% of the work).
It's not too much work if i can find them easily ; if they're mixed with already reviewed one, it's much more work...
To write things short : it would ease the fact of working first on standard (priority), and then on non standard easily (when you've more time).
PS : perhaps my use case is unusual ; i'm used to do things that are unusual to most people