The main reason for changing was to increase the number of cars awarded points in line with the expanded grid. It used to be the top 8 for 20 on the grid , it is now the top 10 for 24 on the grid.
You couldn't give the last place 0.4 of a point, so they boosted everything by 25 to give some whole numbers. The distribution to each place is near enough the same, expect an extra point between 1st and 2nd.
The main impact on the WDC will be when a WDC contender has a prang and limps home in 9th or 1oth to rescue 1 or 2 valuable points. Or in a close finish teh direver with more wins can creep ahead. Of course, if the WDc contender has the extra win point in one race, while the other contender limped home in 9 or 10th, then we'll be in the same position as before