Edit 2 : my crazy theory is that apple doesn't want the mini to compete with their new iphone 6 plus,
If it has better spec, people would surely get the 3g mini. Again, just my wild thoughts on it.
I think this is completely accurate, not crazy at all. A device like the iPad Mini is a huge threat to the smartphone market, especially to phablets. A lot of people now realize that they don't care about actual phone call functionality and would take a device that has LTE data only over a full (more expensive) phone. A lot of people might even be happy with wifi only and just tethering to an old phone (or not at all).