A track record of maintenance is already being established for wind generation equipment and the blades can be 'feathered' in severe winds. There's no way to 'feather' wave generation bouys, they have to ride out storms that can last for days or be destroyed. The U.S. Coast Guard can report on how maintenance intensive navigation bouys are. And navigation bouys are frequently out of service in the winter off the Oregon and Washington coasts.
As for wind power being expensive, wave power will cost more and as the price of oil keeps going up, wind power will become more and more prevalent and vanadium battery technology may allow wind power to be stored until needed on the grid. I am sorry, but wave power, while tempting, is just not practical except for demonstration projects for governmental agencies. There are thousands of wind generators in the U.S. now.