I would guess that the influx of airlines especially Ryanair at major cities like Barcelona and Madrid have challenged margins hugely. Spanair were often very extremely competitively price on domestic sectors inside Spain.
I think that has more to do with than a single accident as lets face it who remembers airline accidents when booking unless there are a huge number with same airline in short period of time !!!!
Anna.aero has an interview with MO'L where he stating its focus is now on Central and Eastern Europe because FR have successfully gained huge market share in Spain and Italy, no doubt they will be looking at more opportunities with the demise of Spanair.
Spanair seems to got caught between its original owners SAS and new owners, with SAS desperate to offload years ago. Sadly its another airline where its place in the market was not defined and management / owners unsure what strategy to follow.
Sadly Spanair's demise is not a shock or surprise.