I am not sure where the term Suicide doors term come from, They are not more dangerous than normal doors and I would believe normal doors has caused more motorbike and bicycle accidents than the Suicide styled. The only thing I can think of it it came out of irony if some one manage to open the door in 200km/h and hold the door handle so hard they would been thrown out of the car.
The suicide doors is very practical and makes it much easier to get in and out of the car especially if you have some kind of handicap or problem to move because of age or pain related issues.
By the way modern cars prevent the rear hinged doors to be opened when the car is moving, It have to be stand still, and in some cases here each side has front and rear hinged doors, ti front door must be opened firs to allow you to open the rear hinged one.