Difference between these configurations
First of all I have to point out both circuits are extremely hazardous and you should not even think about implementing something like this if you are not extremely aware of how this works and the dangers involved both to you and whomever may ultimately be using anything tied to this circuit.

The circuit indicated by the manufacturer does however provide a significantly higher margin of "safety" over your four in series circuit. 

Having two resistors in series in each path increases the overall breakdown voltage versus having a single resistor. Having two in each line also provides a limited amount of isolation between the regulator and the high voltage supply. 

By using proper PCB layout techniques you can limit the incursion of the high voltage to a localized point somewhere near the edge of the board and, if need be, shield it from touch. 

In your four in series example, one side of the high voltage must be passed all the way to the regulator and becomes an extreme hazard. It also makes it very difficult to lay out the PCB to the appropriate clearances and creapage distances.

Further with the four in series, only a single fault to short the series to ground would put the full mains voltage onto the regulator. This would no doubt destroy it, but would also have a high probability of feeding that high voltage out to whatever the regulator is feeding, and potentially at the user.

The recommended circuit, on the other hand, requires two faults in order for that to happen.

Again, I can not stress it enough, this circuit is deadly in any form. Also, do not rely on an isolation transformer to save you.