I've just checked my Nexus 7 (2013) which is also running rooted 4.4.2 KitKat, but has not been reset recently. The BT WiFi app is working on there... And I remember the app having an update recently (after I would have configured it).
So I suspect the N7 already has a stored setup when the new app arrived. Whereas my N4 and DZ didn't.
Conclusion, current BT WiFi app is incapable of creating a new config file in some (all?) situations, but will use an existing one from an older version.
I've had a quick play at taking the preferences XML file over from the N7, but without success. There are some encrypted fields, which may have been seeded with a unique device ID.
I'm going to check my backups to see if I have an older version of the BT WiFi apk anywhere.