With the side impact safety standards the way they are suicide doors are difficult to do safely on modern cars. Most suicide door cars in the past didn't have a B pillar. I believe the Mission E concept didn't either. Most modern production suicide doors are very small moving the C pillar forward to offer some support for the missing B pillar.
Opening the back doors on suicide door cars into traffic is more dangerous also. If a car hits the door, the passenger getting out of the car could get crushed by the door whereas a normal back door will fold forward with less risk to the passenger.
