Why do you say charging wirelessly eliminates the chances of blowing up/catching fire? Did you see something that diagnosed the fires to a problem with the USB port? Batteries heat when they charge. Just because you use induction instead of direct current to get the energy to the battery charging circuitry doesn't eliminate that; at the end of the day, the circuitry is going to convert that energy to current to recharge the battery and this is likely where the failure occurs as the charging circuitry fails to detect the battery is full and keeps pumping energy in.
Aside from that, your point about 35 out of over a million being a low failure rate is somewhat valid. The problem here is that the failure is a bit more catastrophic than the battery failing to charge or a screen cracking. These kinds of fires could result in some pretty nasty consequences for a phone left charging in a car or plane carry-on.