OS X prefers case insensitivity but TimeMachine seems to require case sensitivity? As per What are the downsides to using Time Machine? the first item reads Time machine requires an Apple specific HFS+ filesystem to store backups. Which is a Mac OS Extended (Case-sensitive, Journaled) disk. But then, OS X of course wants Mac OS Extended (Journaled). Just like most everyone else I get:  

This volume has the wrong case sensitivity for a backup.  

After hours of googling, I've not read that there is absolutely no workaround.
The linked answer doesn't say that Time Machine requires ...Mac OS Extended (Case-sensitive, Journaled).... It only says Time machine requires an Apple specific HFS+ filesystem to store backups and it should be read as the Apple specific HFS+ filesystem.

With other words: Time Machine can't backup data directly to NTFS/FAT32 or EXT3/4 volumes.