Same here. I write a lot of notes in markdown that I sync using Dropbox. I often want to read and edit those notes on my phone or ipad, but I don't remember the exact file names.
Similarly, I wish photo apps had a "use most recent photo" button, instead of making me select my photos, scroll down to the very bottom, and click on the last square.
I toss PDFs I want to read on my phone into dropbox. This use case happens often for me. I have to consciously rename the PDFs I want to read in the next few moments with prepended names like ! so they appear at the top.
I have folders with tons of photographs in them that I upload from my desktop. Whenever I'm on my ipad or iphone, finding a picture I just uploaded is an absolute nightmare if I can't remember the name ... I usually have to go load up dropbox.com in my browser, do the sort there and download the file.
I guess my particular use case doesn't occur that often :(