If the blackbox of MH370 were to be found today, would it actually still provide any information, assuming that it was in 5km deep water or so for some 5 years now? If not, why would you still be looking for the missing aircraft and especially the blackbox, if there was nothing to find out about the reason that caused the 777 to disappear?
There are precedents: the flight recorders of AF447 spent two years at the bottom of the ocean, and revealed all that had happened after being retrieved. So they had survived being immersed in salty water at high pressure, making it very likely that MH370s boxes have survived as well.
Time of immersion is less relevant: oxidation (rust forming) is much slower at greater depth, due to much less dissolved oxygen and lower temperatures. The corrosion that does take place is mainly anaerobic, through bacterial sulfide formation. As posted in for instance this link.
If not, why would you still be looking for the missing aircraft and especially the blackbox, if there was nothing to find out about the reason that caused the 777 to disappear?
In fact we are concerned with 2 black boxes, the flight parameters box, and the voice recorder, these are complementary. The voice recorder is extremely important too, for instance in the Ethiopian 737 MAX, the voice box recorded the repetitive action of the pilots searching for an adequate procedure in the paper checklist
But not only
When a crash occurs, the debris, and every part of the aircraft is capable to talk. For instance it will tell if the crash occurred while trying a ditching (water landing) or not - such as falling like a stone due to a stall.
Families are concerned, people are concerned, memories are concerned. Don’t be just materialistic, finding the aircraft will help these families to mourn their beloved parent.....