Every technology is flawed.It is flawed technology
There is no such thing as 'works 100% of the time with accuracy and precision'.
Au contraire- it is something that is exceedingly good for the sport- it takes away the controversy.Cricket is a game, a sport. Luck is apparent in our sport, and often can give fans high's and lows, depending on who fortune favours at that time. I think replacing this with something as mechanic as Hawk-Eye is dangerous to the sport.
Video replay is extensively used in NHL to determine a goal and crease violations. As such, there is hardly ANY controversy in the NHL about goals.
I have no problems in reducing umpires to nothing more than the showboy who calls for tea in the middle, if that is the more accurate option.
If the very fundamental nature of the sport can be altered through technology(such as batmaking, ball-making,pitch-making,pad-making etc.), there is no reason why umpires should be immune to technology at the face of their incompetence.