Why don’t they use non-bird harming turbines? There are several new designs for this.
http://www.ecochunk.com/3063/2012/10/13/windstrument-scalable-wind-turbine-is-safe-for-birds-too/
The center 40% of a propeller or rotor does very little work. This design does not look very efficient.
The main problem with wind power is that it is inconsistent in most locales. Those that have reliable high wind speeds tend to be either unpopulated and thus no local demand for power or they are populated by the idle rich who delight in protesting the spoiling of their view of the mountains or the beach.