Yes, MS has fewer fires than ICE cars statistically up to now, but MS now has far MORE fires than Leaf and Volt. Obviously because the MS battery pack is a much larger and exposed target, with lower ground clearance compared to those vehicles.
This is not acceptable for the "best car in the world."
Seems to me the short term solution is a software update to make the low setting higher (maybe 1 -1.5" higher than it is now) while they work on a better armor system and/or deflector to protect against and/or mitigate the damage from road debris.
In a nutshell, "damage control".
Hopefully Tesla is hard at work on something like this and we'll hear about it very soon. Short term big problem for Tesla, but in the long term I think it will be a blip (just like the early Volt fire problem was for GM.)