Nice chart, F1Y.I've knocked up a quick chart based on the Turkey overtaking figures comparing starting and finishing positions and then number of overtakes.
View attachment 1478
It is showing how most of overtaking didn't really change anything, the only exceptions being Kobayashi and Buemi. The two drivers who did the most overtaking actually went backwards during the race.
This analysis has pretty much made my mind up, the improved overtaking has no relevance on the race result but makes the race more interesting to watch.
I have two reservations on your conclusions though:
a. The chart doesn't show up the effect of a driver losing a places, either off the grid or through a spin, penalty etc. then overtaking perhaps several cars to make their way back to their original position. A minor example of this would be Hamilton, who you could say had an effective starting position of 6th, not 4th, for the purpose of this exercise (a better example would be his 2006 Turkish GP2 race, where he spun on lap 2 from 6th place, re-joined in 18th and then overtook the field again, including Timo Glock and title rival Nelson Piquet to finish 2nd). Maybe an extra column for 'lowest position held during the race' would help, but then again that would be falsified by pit stops anyway.
b. The simple fact that the nearer a driver is to the front row, the fewer opportunities he will have to make overtakes anyway. So the drivers who start and finish high up the order, unless they drop back and make places back up as in (a), will always have relatively few overtakes to their name. Webber for instance may have had only two overtakes at Turkey, starting and finishing 2nd, but his figures for China would have looked a lot different.