I think the final sentence in this article says it all...
"So what accounts for the difference? Perhaps it’s simply a question of more cars on the road equaling more accidents — and more fires. After all no car, whether powered by gasoline or electricity, is immune."
Personally i I couldn't agree more with this. At some point this much stored potential energy will want to catch fire - whether electric or gasoline - all that is required in either case is the right (or wrong..) trigger. There weren't any Model S fires until the number of vehicles and accidents got to be sufficient that the probability of a fire reached a realistic threshold.
But from my personal viewpoint, the biggest thing in favor of the Model S is the characteristic of the fire itself. These vehicles are not exploding. They are starting to smoke and then eventually catch fire several minutes after the triggering event, and also after the occupants have already left the vehicle which notified them that it was experiencing difficulties. No gasoline car has the ability to notify you that it has a problem that might lead to a fire (except for low coolant and/or overheating related fires) - for the simple reason that gasoline related dies do not occur in parts of the vehicle that are subject to computer monitoring. They are, by definition, an uncontrolled unmonitored total failure of the system. In the Model S (and any liIon battery system) the battery is constantly being monitored as a necessary function of the car. In the unlikely event of a thermal runaway occurring that the battery is no longer to control through cooling (because, for instance, it was punctured and there is no coolant remaining) the system is still aware of what is happening and thus notifications can happen. Also the design of the Model S battery is such that these fires have been contained within only a small percentage of the total battery - and the heat is intentionally vented to the side to avoid the passenger cabin.
Frankly I for one feel safer in my Model S than I have ever felt in any other car, period. And to know that a battery puncture fire is now a warranty and not an insurance issue is quite simply incredible.