I think you are too gloomy in your assessment thirra.

Marine technology has been around a lot lot longer than wind... and we can use pretty well bog standard materials. Non of the fancy high tech composites.
The corrosion problem exists but is 'solvable' ... instead of Zn blocks, we now use Al blocks.
Yes there are stresses, but in all likely hood less than the torsion stresses experienced by large super tankers.
North sea oil rigs are pretty robust structures... and think of those rigs that got blown around by Katrina but survived.

Wave is more predictable and measurable than wind. Our over the horizon radar can see the ocean state 1000s of kms away... and since the 2004 tsunami, there are more ocean wave buoys out there.
For the same amount of energy a wave power unit can be smaller simply because the density of the working fluid is greater.
And also the wave field is more consistent... unlike wind, which can be gusty.

The issue for wave has been the coupling or transforming mechanism. The device mentioned in this article sounds very promising. The units are much smaller than a wind power unit of the same power. I think units can be placed closer together as well.