If it was "intentional" then can they not up the charges to "premeditation?" I think knowingly driving your car into a crowd of people, at a high rate of speed, makes it pretty clear her intention was to take people with her in her "suicide attempt." Doesn't sound any different than the mass shootings, but she used a vehicle instead of a gun as her weapon of choice.
It sounds like a very lame attempt at suicide and a much better attempt at murder. My guess is that they want to go with what they think they can prove. If she is convicted for second degree murder she could still get a very long prison sentence.