I'd actually read that article before I posted. It's great as far as it goes. Expanding "other" is an old Apple problem they don't seem interested in fixing.
However, what's happening to me isn't a slight increase. My Other became 81 gigs. After my third restore-to-factory-and-reload-everything, it was back to a normal size. Now, my phone only has about half the music that's supposed to sync. Half-albums. Songs missing. But at least the Other category is a tiny 1.8 gigs on my 128 gig phone. However, this happened last time as well.
iTunes apparently can't copy massive numbers of files to the phone without completely screwing up the device. That means there's no point in owning a 128 gig phone, unless you're willing to manually copy all your music files because iTunes screws up your phone if you do it any other way. As it is, each time I plug in, iTunes starts copying over still more music files, despite the fact that it said it was sync'd already. It's just a matter of time until I plug it in again and see, in real-time, the image of other jump from 1.8 to well over 25 gigs. In and instant. The graph comes up, the sync starts, and a few seconds later there's not enough room on my device because the other file is huge.
I realize this must have something to do with how it's syncing songs. And of course it's unreasonable of me to expect Apple to have mastered the amazingly complex "copying a file" process. It's not like they've had any experience with "computers" or "music" before. They're just Unfrozen Cave-Man Programmers. Our devices and ways are strange and frightening to them.
Thanks, Apple. I'm just counting the days until Other explodes again and I return this worthless device for the 16 gig version. If you won't let me use the 128 gigs of space, I want my $200 back! It's bad enough they price gouge for memory, but to then have software that can't even handle the file copy process is absurd.