Mac OS 10.10.5 (Yosemite)
After getting the crash discussed in this thread, I tried the suggested remedy:
Applications $ Bitcoin-Qt.app/Contents/MacOS/Bitcoin-QT -resetguisettings
...which brings up a "Welcome to Bitcoin Core" dialog box that says since this is the first time the program's been launched the entire blockchain will be downloaded. I guess I can do that, but do I have to?
Did I misapply the remedy by trying it only after running 0.15.0 without it and getting the crash, instead of on the first run?
If you had chose a custom your data directory the first time you ran Bitcoin Core, this behavior is expected. It is to ensure that you choose the same data directory again so that you don't have to download the blockchain again. If you do use the same datadir, then it won't download the blockchain again.