> Given how cheap flash is these days
Flash data retention at high temps is TERRIBLE (and gets worse for MLC/TLC/etc), see any flash datasheet. It is NOT nearly as simple a problem as you might think.
Yes, it is a solvable problem, but please do not dismiss it so outright as "trivial"
[1] https://mentourpilot.com/who-doesnt-want-25-hour-cockpit-voi...
Exposure to super-high temps occurs in a small set of circumstances, all of which overlap with the destruction of the recording device and the cessation of incoming data. So we only need the same 1.2GB (or whatever) of high-temperature-tolerant storage.
The 25 hour storage can be on normal flash, as if we're more than 2 hours past the incident and data is continuing to come in, then the incident of interest did not destroy the airplane, and the flash will have remained within its normal operating parameters.
In addition to not giving up that requirement, we could also add a longer, not-heat-tolerant storage. If it gets destroyed in a fire, see the above paragraph. If there is an incident where the data is of interest and the aircraft is not destroyed in a fire, then this will maintain the data long after the above system has deleted it.
No one has advocated giving up the high temperate storage.
It's a material science problem, and other forms of media are affected by high temperatures and physical deformation just as much as flash if not more.