IIRC, the black box data is recorded on a steel wire, because this has much greater survivability than any sort of magnetic tape would. I have no idea how flash memory or something like that would compair to this in survivability.
As others have mentioned, we have to remember that this is literally a once-in-a-lifetime event. About 99.999999999% of plane crashes don’t need anything close to 2 hours of data to let the authorities figure out what happened.
ISTR that they use solid state memory these days… no cite, except for my memory watching “How It’s Made” on the Science Channel a few months ago when they re-ran the episode about black boxes. Or maybe it was “How Do They Do It?”… one show or the other anyway.
Yes, they are solid state now. No cite to hand, on the phone, but the wiki article would back it up.
Indeed, when was the last genuinely mysterious airplane loss? Certainly, if you go back to something like the Dole Air Race, there’s plenty of planes which went down in regions outside of our ability to recover and analyze. But since the commercialization of international travel, how far back do you have to go to find something that’s largely or completed unexplained?
This might be the first case ever where two hours of recording time won’t be enough. And very likely there won’t be another one for a long time.
Although the current generation CVRs record for 2 hours they are actually only required to record for 30 minutes. If you are wondering why the manufacturers and airlines are willing to pony up for a 2 hour recorder when that is not required but have not been proactive in installing recorders with even longer recording times, the answer would be that the NTSB has been recommending for some time that the requirement be increased to 2 hours. The manufacturers are ensuring that they have CVRs capable of meeting an expected future rule change. This is a cheaper option, long term, than designing to the current standard only to have to refit more capable recorders at a later date. I suspect that if the NTSB had been recommending 10 hour recorders we would probably have them already.
If they’re using solid state memory - is there really a cost / weight difference between two hours and effectively unlimited recording? For Solid State - what other factors would come into it that make limiting the time to two hours any different to fitting something that simply records an entire flight - or even a month’s worth of flights?
What if it has the crew and passengers doing karaoke?
Thank you , thank you , thank you for making my day. 
You win the thread!