Ok,
Here is a capture from PS4 I just made without the temporal AA step applied. (Ignore the yellow text from the development build)
You can clearly see our standard PC/XB1 motion-blur shader visible - it's exactly the same runtime code, shader code with same number of motion samples and the same full HDR texture resolution!
The road has that "lovely" motion-blur speed look that you get with this method using multiple samples.
Now you might note that the armco's and some of the scenery are less blurred than some of the images posted around here. This is because the motion *velocity* shader parameter is reduced on PS4 - the temporal AA post process (through persistence of vision) also adds to the impression of motion blur - so if we kept the motion velocity scale the same as XB1/PC there would then be to much MB.
If we implemented an option for allowing the temporal AA effect to have sort some of slider as has been mentioned then the traditional Motion Blur velocity scale would be change inversely to the scale of the temporal AA effect. The motion velocity scale could be also be on a seperate slider on all platforms - since it's the exact same code.
I hope this explanation gives the community here some further clarity on why isolated image analysis isn't always the full picture........ (badum!)