Cockpit Gradient and unstabilised approaches

Safety Research Case Study The approach and landing phase is usually the most critical and most dangerous phase of every flight. In 2011, about 65% of all accidents began in the approach and landing phase (Trautvetter, 2013). The main cause of the accidents and incidents in this phase is an unstabilised approach. Much is being done to mitigate this prevalence the core of it being training. On average, 96% of unstabilised approaches do not result in a go-around when 54% of all aircraft accidents could have been prevented by a go-around (Trautvetter, 2013). A stabilised approach is defined as:
The aircraft is on the correct flight path;
Only small changes in heading/pitch are necessary to maintain the correct flight path;
The airspeed is not more than VREF + 20kts indicated speed and not less than VREF;
The aircraft is in the correct landing configuration;
Sink rate is no greater than 1000 feet/minute; if an approach requires a sink rate greater than 1000 feet/minute a special briefing should be conducted;
Power setting is appropriate for the aircraft configuration and is not below the minimum power for the approach as defined by the operating manual;
All briefings and checklists have been conducted;
Specific types of approach are stabilized if they also fulfil the following: ILS approaches must be flown within one dot of the glide-slope and localizer; a Category II or III approach must be flown within the expanded localizer band; during a circling approach wings should be level on final when the aircraft reaches 300 feet above airport elevation; and,
An approach that becomes unstabilised below 1000 feet above airport elevation in IMC or 500 feet above airport elevation in VMC requires an immediate go-around (SKYbrary, 2013).
A good example of recent case is Asiana 214 in San Francisco.

Research Question
Why are unstabilised approaches still so prevalent and why are flight crews not conducting go-arounds when one is recognised?