I just couldn't resist such absurd/insane examples as the trademark of the renewables crowd.  Saying physical 'footprint' of a turbine is its only effect, in restricting land use, is just silly.  The dissonance is deep within you and denial is likely not to change.  

Using YOUR OWN example of 20 turbines/Km2, the efficiency of a 2Mw turbine is accepted at 20-25% (lack of wind/high wind, no demand, maint., etc.) means that 2Mw turbine produces 400-500 Kw of ACTUAL SUPPLY.  Plus, without solving the storage problem (and there are NO solutions in the pipe) it's all instant demand.

SO, to have 2 Mw OF ACTUAL CONTINUOUS SUPPLY requires installing 4-5 turbines. Since the grid requires 7x24 supply there must be a watt-for-watt back-up for continuous demand.  So to get 2 Mw of continuous supply REQUIRES the installation, conservatively, of SIX (6) or more turbines.  That means your "20-turbine" example immediately turns into 120 OR MORE.  Now figure that for 1100 Gigawatt generation (US).