Lets go back to the start for a minute
While there is a lot of conjecture as to what happened when (and the releases so far don't clear much of it up), it seems nobody is disputing that the airspeed sensors shut down (for whatever reason, and for now everybody is saying it was icing, so I will assume for a moment that is correct). While everybody is focusing on the eventual stall, the "for the want of a nail" event was the loss of airspeed data.
The loss of airspeed information is a big deal, especially in this aircraft.
I'm asking myself what was this aircraft doing in a situation where the loss of airspeed was not uncommon?
Coming from my experience with aircraft certification, I don’t believe that the reliability of those pitot tubes would have been considered acceptable in the initial certification if they were presented to the type board. The requisite reliability of sensors such as these is 99.99%. The net result is that you can have failures due to old age and part wearing out, but that high reliability requirement limits failures to random events (one sensor at a time, something the control can cope with). The demonstrated reliability of the pitot sensors was much lower than that, and when Airbus realized that it was they should have not just issued a recommendation, but should have had EASA issue an AD for the replacement of the parts, as well as require flight restrictions on the aircraft until the AD was carried out. The was a high probability of multiple sensor failures in these conditions and the impact on pilot workload makes this action, in my mind mandatory.
To put it another way, if Airbus went before the type board and said “these sensors are 99.99% reliable, except when they are flown into known icing at high altitude, in which case they are 95% reliable, and OBTW, when one fails you generally get multiple failures”, the type board (when they stopped laughing) would have said “fine, you can fly the airplane, but you aren’t going to fly it at high altitude into conditions where you could get that kind of icing”. If the reliability of the sensors, under specific conditions, falls below the certification standard then the certificate holder has a responsibility to notify the certification authority and issue an AD with a restriction on the flight envelope until the reliability issue is addressed.
Hard to believe that Airbus would leave themselves open to this kind of potential liability by not making sure an AD was issued as opposed to the "recommendation" that went out to replace the sensors.