Currently, death messages are turned off due to past exploits which used to make player crash.
It worked by sending a message that was way too long for minecraft to interpret without crashing if I'm correct.
Here is my suggestion:
We cannot re-enable vanilla death messages, obviously, but we could re-enable them by simply making a custom death message, it could look exactly like the vanilla one but stripped from anything dangerous (Anything over x characters get stripped away, any dangerous click actions removed, etc).
Covered by https://forum.totalfreedom.me/d/1512-death-messages
Now, some players may also be against it because "People could just spam death messages".
I believe this would fall under the do not spam rule, but, we could also make this a non-issue by simply making them togglable per client, kind of like you can disable the discord bridge in-game.
Adding vanilla features back is currently a huge issue amongst the community, so expect more suggestions like this as to how to "fix" or add back removed vanilla features.