I thought moveable wings are already in this season?
Pressing 1 button (or dealing with 1 task), at a time, is not difficult.
Pressing 2 buttons (or dealing with 2 tasks), at a time, is not difficult.
However, if you have 10-20 buttons (or 10-20 tasks) to deal with at a time, all of sudden things get difficult.
The ability to multi task and to hit buttons fast with little thinking time, becomes important. The more buttons you have to operate in a corner or a lap, the greater the chance of making an error.
KERS will be an additional task which the driver shall need to deal with if it is introduced.
If you go back to the mid-90s (and earlier), steering wheels were simple and all the driver had to do was steer, brake, change gear and press the throttle (and maybe a clutch). I believe brake bias could also be altered. These days, the driver has to do all those things and a whole lot more. Hand eye co-ordination has become much more of a factor in F1 than it was 20 years ago.
And also as was mentioned earlier. KERS is not about who presses the button quickest/reflex related. Its about using it at the right place at the right time.
As I said above, if you have many tasks or operations to deal with during the course of a corner, you are more likely to make an error. A person who has good hand eye co-ordination and is used to memorising button locations/sequences will find this easier than someone who isn't used doing this.
Computer games involving fast key presses improve your hand eye co-ordination.
It seems his good "hand eye co-ordination" was not enough to take avoiding action pertaining to the 3 incidents he was involved in
Unfortunately, no amount of buttons or key presses can save Hamilton, when he is already in the middle of an accident.