Although if your into repeating the same thing and expecting different results, they have a room for you at Betheseda.
Umm, not sure if you meant to tie those two thoughts together. This was at least the second launch with shedding foam, and IIRC, was about the ninth with shedding foam. All previous flights that experienced shedding foam at liftoff returned without burning up on re-entry, so perhaps the mission managers were into repeating the same thing, and getting the same result.
The degree of damage is assessed, obviously with care, after each flight. While there was a desire to reduce the damage to the tiles, the concern and motivation was turnaround (I have heard that at least twice, and assume it means time/cost to make ready for next flight) and not loss of vehicle.
You could make the same assumption about russian roulette, but no one will say it is safe, even if you beat the odds for a consecutive period of time.
If your made aware of the possibility of disaster, you eliminate that risk or kapow you lose.