The European Wind Energy Association says (PDF) development of floating wind turbines in deep water should be encouraged, as the amount of power they can generate is vast. Note: The turbines are indeed on floating platforms but are tethered to the ocean floor.
Using only North Sea sites with water over 50m deep as an example, the potential for deep offshore wind energy is vast. 66% of the North Sea has a water depth between 50m and 220m and could therefore be used to deploy the deep offshore designs. For illustration purposes only, assuming 6 MW wind turbines, the energy produced in this area could meet today’s EU electricity consumption four times over.