Are plane's black boxes essentially useless tool in the modern age and how to improve upon it?
We have this topic well covered here, here and here (which is the granddaddy of them all).

Basically, it comes down to two issues:


Regulation: It takes a long time for innovations to be approved, especially in safety-related applications.
On long-range flights there are long stretches of no radio contact (except maybe for a satellite connection), so streaming becomes impractical due to the data volume.


Black boxes have been improved a lot since their introduction and they continue to get better. Please let the investigators find and analyze the recordings first before jumping to conclusions.