Most sports have a high risk of serious accidents due to physical contact from others(rugby, AFL, NFL ext) or from an object moving at a first pace (cricket, cars in motor racing, squash ball even) compared to say your usual 9 to 5 job working at an office in a call centre. Theirs obviously varying risks in each spots, but you'd like to think most sportsmen know what risk is in the sport they are performing in before they decide to try and make it a career and participate at the elite level in it.
All you can do at the end of the day is minimise the risk as much as possible which i think cricket has slowly done over time. Watching older games where players wouldn't even wear helmets when batting when I was younger, I just couldn't believe it! After the steve smith incident maybe you could argue that players should have to wear neck guards now? Wearing pads, arm guards, a box and helmet is definitely reducing the risk now, but you're never going to make the risk of being injured by a leather ball being bowled at 150km/h 0%.
The bouncer has been a ball bowled 1000's of times now and I think their is no reason whatsoever it should be banned or minimised as a knee jerk reaction to a couple of freak occurrences.