OK, I'm going to wade in with my 2 cent';
In my opinion the (apparent) lack of overtaking can be attributed largely to the absence of mechanical grip within 0.5s of the car in front. How many times do we see one car that is clearly faster than the car in front stuck for lap after lap behind a slow car and simply having to sit there until the mobile chicane pits, or makes an error?
When a car is faster than another it should be able to overtake - However, the reliance on aero makes this impossible unless the 'actual' difference in speed is about 2-3 seconds per lap - then they are able to out-drag the slower cars if there is a decent straight.
Of course the current regulations mean that the cars are heavily reliant on aero and this is their problem. The driver aids ensure that errors are minimised and that means the car following can do nothing until there is a HUGE mistake.
Personally I don't go for stripping the cars of all the sexy technology - that's really the reason I like them - but a faster car should be able to overtake a slower one... surely that's the point of racing
I would like to see driver skill brought back more to the front too; I think traction control is a bad thing; drivers that put the power down too hard should be punished, either immediately (with a spin), or later when their tyres are shot. Bigger run-off areas, so that a spin doesn't end their race, but costs them time.