I don't know why the feature was disabled again, but I guess ppl were complaining about having their health counted down in pvp.
That isn't a problem in dtv and I'm sure lots of ppl want to know how much damage they do with certain builds/weapons. They could always join dtv then for testing and pvp would stay as it is.
Except for one person, I only saw positive feedback for the feature as long as it lasted, so why completely remove it?