These turbines require extensive maintenance and repair. To effect major repairs one must remove the turbines from their towers. If you think that's easy or inexpensive, it isn't!
IIRC only about 25% of the typical utility bill covers the cost of fuel. Mostly it is for maintenance on power lines and generating equipment and, of course, taxes. Maintenance of windmills, as you point out, will be much more labor intensive because they are so widely dispersed.
On the bright side, none of these jobs can be exported to India or China.