Man, its getting boring these days...
That's why I don't post anything in LFS forums weeks on end these day. I REALLY wish the next patch comes with significant aero and turbo updates. Last thing I want whilst racing against the clock or others is a stupid AI car to mess it up but......
Anyway, high nosed (and winged) cars have 2 obvious advantages.
1. Lack of ride pitch and ride height sensitivity
In both CFD simulation and RL aero tests, its has been proven time and time again that the LOWER you run a front wing, the better the aero for all parameters that matter to a race car (L/D ratio, etc). This is true only up to a point, however, just before viscous effects come to play and the airflow under the front wing drops to Zero....
Note that modern regulations force quite reasonable front wing ground clearances to vastly attenuate chassis attitude sensitivity issues, mostly out of safety concerns.
2. High nose reduces nose to wing interactions
Ideally, the wing will act as a wing on itself. In practice, that's impossible as they're meant to be there to make downforce. So to let the wing act as efficiently as possible and ensure maximum control of airflow, you want it to be as decoupled from nose airflow as possible. This is achievable by using really high noses and setting a reasonable distance between the wings mount and the nose.
Of course , the above are quite general explanations and aero is still very much a black art of sorts, since real life aero behavior is both notoriously complicated and in most cases impossible to model in a completely analytical manner. That's why there's CFD that relies heavily on the use of basic equations of aero, heavy numerical calculations and approximations and of course shear computational brute force. That's why teams like BMW Sauber invest millions in Supercomputers such as Albert (or was it Albert 2? I think hey have 2 but can't quite remember ATM...). Aerodynamics of an F-1 car are complex and full of complicated interactions that should either be eliminated or exploited, so all I said should be taken as a general guide, not absolute gospel.