It doesn't give you much reaction time either.
so it increases the chances of you making a bad decision... but it's the bad decision which causes the crash !!
No. The problem is that human capability cannot be increased to cope with the shorter and more critical reaction time. Therefore the faster you travel the more likely you will make a mistake. Lets increase the speed to 350mph - but the cars is still controlled by the same human with a brain operating at the same speed as it does at 70mph. If cars were human-less there wouldn't be a problem with higher speeds - but we can't operate our brains at higher speeds and that is the crux of the issue.
Martian. If you and your family were involved in a motorway pile up, would you rather it be at 70 mph or 80 mph. Personally I'd rather see the limit reduced to 60 mph. If you are in a hurry then leave home earlier.