If you take into consideration one historical information regarding (Windows version of) Send to Kindle app then you can come to a conclusion what type of "geniuses" Amazon hires.
STK Historical information = years ago STK app used to read and use mobi file's title and author metadata to pre-fill those two inputs in sending UI dialog and then developers "improved" it to ignore metadata and just use filename for title and whatever for author. And this is the way STK Windows app work till this very day
So from having and option to overwrite / override bad metadata when and if it happens to be wrong to having to edit both input fields for every book you're sending.