Why do they still need the flight recorders?

Shouldn't it be possible to send all information they store in the flight recorders to a server somewhere on ground instead of saving the information on the plane? I guess not since they don't do it but why can't they do it? Does anyone know?

The cost to do so to air accident investigation standards would be extremely high compared to the current set-up - particularly given the unreliability of data transmission to/from fast-moving objects, the likely disruption of the satellite communication link if the aircraft is in unusual attitudes (very common just before a crash), and the likely buffering/time delay in getting the data off the aircraft and off to the satellite even if you don't lose the link because of an unusual attitude (even the current real-time on-board recording set-up often leads to really frustrating data losses in the last second or two before impact).

When you weigh the cost of trying to do this and the disadvantages that you thereby import into the system against the extreme rarity of the complete loss of the recorders, the current system is probably a better overall solution.

In addition, there are other things on which money could be better spent to improve investigations - the primary one IMHO being video recording as well as voice recording.

Thanks for the explanation.