This 50% rule is the main loophole in DRS or umpire call.
It's not a disadvantage to batters imo, it's just you are empowering the toothless bowlers. When the ball actually kisses the stumps, bails get dislodged it doesn't matter if it's 1%-10$ or so on. You don't say that it's just clipping or batters are in a disadvantage.
So why give benefit of the doubt to umpires and batters when it comes to LBW?
OK.. then maybe we can agree on that. But time is also important. I just hope that the players will not waste too much time in appealing and reviewing the decisions. From my perspective, the only disadvantage with DRS which I have observed till now is the wastage of time in reviewing the decisions. And in some cases, the players just review them, just for the sake of it. Finding the right balance between 100% accuracy and finishing the matches on time is very important.