Hi Hans :)
First, when your system is so bad damaged, that you need to reinstall thecomplete OS, all the setting of the can stay untouchable. These are passwords, desktop settings, addressbooks and whatever.
In my home there are exactly those configs you mentioned, but no data, such as large audio productions, just a few pics etc., however, if my Linux gets broken I restore it from a backup, including my home. Even for a new install I could restore /home from a backup, this isn't work and only takes minutes. When doing the backups I even can backup folder separated.
Second, when space is getting low on /home, it is easy to add a new device and put users data onto it on the new device. This can be also done while the system is running (special hardware needed). This might be more important on servers, but may also become important on desktp systems or notebooks with 2harddrives built in.
Now we could extend this discussion. I for example use MBR with averaged partitioning when ever possible, because IMO it's the most comfortable to use ;).
Third, security. You can just encrypt the /home partition, whilst the rest of the system can be left in unencrypted state (especially better fortroubleshooting purposes)
You can encrypt the /home folder too ;).
Fourth, if you are using /home on an own device, you can carry it around, while got every personal setting with you.
You can copy the data to something smaller, if you need those settings elsewhere. I never did and I guess we aren't talking about an averaged home PC anymore.
Regards, Ralf