The reason that high speed cornering makes overtaking difficult is the means by which current F1 cars achieve those high speeds... through aerodynamics. It is perfectly possible to pass in high speed corners, there you can take NASCAR for example at 190+ mph (and at half or less the g-loads of F1!)
As for drivers complaining, some currently are! TGF, Trulli, Fisi, and others have voiced that opinion so far this season. But some drivers (Panis comes to mind... not that he has to worry about travelling all that fast in the Toyota
) disagree with the notion that F1 is too fast, they like it how it is...