You mean other than the fact that they're like 100x more expensive than nuclear?
Building a single windmill prototype like that and sticking it alone in the ocean (with a 10 kilometer power cable) is bound to be lot more expensive per MW than building a whole farm of them. The original article also does not specify how much of that money went into development and how much went to actually building the turbine. The cost should come down quite significantly if that thing actually works as advertized and they start building them by dozens.
Your claim that nuclear is the only option for affordable and ecological power is either pure trolling or rather incredible stupidity and ignorance. I agree that it's propably the best current short term option, but it definitely isn't the only or best one in long term.