Currently, Jessie installs Kodi from the Raspbian repo. Wheezy uses the package provided by Michael Gorven. Both of these are 14.2 the last time I checked.
The only reason 15.2 is not installed is because compiling Linux software is not my strong point. Its one of my demons that I would love to change at some point
I don’t know if this is related to the Kodi version but something strange happens to me with the 14.2 release. I have a pendrive that works correctly on my OpenElec6/Kodi 15,2 image, but when I try to get it working on DietPi/Kodi 14.2 it doesn’t get mounted.