It's unnecessary and it doesn't really do it's job. Your DP flashing red doesn't actually mean jack **** because you can usually still push rockets, deflect and parry like normal.
No, but it does mean that one or two more unparried hits with a saber or a few more laser blasts (especially if your running) will kill you, so its not without its use. It also means your vulnerable to force power or superbreaks as well. I don't mind if the sound is taken out, but there should still be at least some sign that you're at critical.