This has been a terrible week for light aircraft/private aviation. A report on the death of two young children caused by irresponsible actions and another two children killed for reasons we do not yet know.
However, in both instances, it seems highly unlikely that any form of aircraft safety equipment would have made a difference to the end result.
I notice that some people try to draw similarities to motor racing or the wider automotive industry. There have been incredible advances in these areas but at equally incredible cost. That sort of money is just not available for the relatively small private aviation market.
So, to have a go at answering the original question and at the risk of stating the obvious, the AAIB bulletins have been required reading for me over many years and they seem to suggest the following:
If a light aircraft is flown in a simple A to B way by a current pilot who has received normal PPL training , it is highly unlikely to break up in middair and apart from the odd occassion where maintenance has been called into question, the flight should be of relatively low or acceptable risk.
Once low flying, formation flying, aerobatics, bad weather flying, non currency and so on are introduced, if the pilot is not properly and comprehensively trained for these activities (and current), then the risk increases significantly and the sad tales from the AAIB reflect this. I would suggest it is therefore hard to come to any other conclusion that fault in most cases lies with the pilot and not the airframe.