I think (but sure lets check it) he disabled it since when the cache filled up in symbian there was some unexpected results. Some symbian phones do not have much disk space in them. And if/when the temp cache is in C (like the comment in code says) there's really not that much room.

In N9 there should be plenty of room.
I did not check yet though that is there some limit coded to the cache size in the map plugin(s).