Airplanes broadcasting parameters, why not? Or am I missing something?

Airplanes crashes are unusually high in the last few years. It's of everyone's best interest to avoid such situations. Why doesn't airplanes broadcast its parameters over VHF radio & save received parameters and upload the data to a cloud service when descending (with regular 3G / 4G) or landing time (over wi-fi)?

The parameters might be everything available from whatever buses are found inside an airplane.

The system should operate on a best-effort approach, which means it could be useful as a starting point of investigations regarding accidents, failures to comply with air safety rules, and so on.

What am I overlooking? Is such technology already being deployed somewhere experimentally?

The data should be textual for easiness of expansion and should everything sent should be recorded 'as is', with no warranties whatsoever to be clear, not fraudulent, or complete.

Compression (say, regular gzip or whatever is easier to recover partially if received with errors) might be used to make it possible to send more information at a time. Airplanes might even alternating send uncompressed and compressed data, one after the other.

If this is treated as a best-effort approach a lot of room for experiment and adaption could be found (what can be very complicated for industrial applications in this field for obvious reasons).

The data available should be public available for anyone and choosing to broadcast parameters should be a voluntarily action (not enforced by law).

Submission to the database / cloud service must be made using regular PUB-key cryptography we use daily on the Internet.

Disclaimer: I've no knowledge of avionics, but I've read some books on the subject of industrial accidents and would like to know more about it.

Nice books: 1. Normal Accidents: living with High-Risk Technologies 2. The Logic of Failure: Why Things Go Wrong and What We Can Do to Make Them Right 3. Inviting Disaster 4. The design of everyday things