It's not often I jump to Ryanair's defence, but must agree with asheng on this.
The continual attack on quick turnrounds per se (based solely on turnround time rather than amount of handling activity) becomes very wearing after a while.
Take a 'traditional' airline's 737 turnround, surrounded by catering vehicles, cleaners, freight (including animals, hazardous cargo), change of cabin config, and a cast of thousands, etc. etc. Now try and squeeze that down to 20 minutes and, yes, you have a dangerous situation.
However, strip out a lot of the unnecessary elements and simplify it to a 'passengers and baggage' only operation ("low cost"), with minimal ramp activity, and IF PROPERLY CONDUCTED this is no more dangerous, and probably in some cases inherantly safer, than the more complex and congested turnround.
I don't know the circumstances of this tragic accident, and my sympathies to all concerned. Let us all learn from it. However, let's not start another round of "quick turnround = unsafe" style discussions!