I think this is a helpful perspective-- it's not about blame, it's about advice.
It's not your fault if you have your personal photos stolen, but that doesn't change what my advice would be to anyone who is concerned: If you don't want someone to see your nude photos, don't allow nude photos to exist.
And on a side note, I don't think the idea is correct that these celebrities did an effective risk/benefit analysis and found that the benefits outweighed the risk. First, because I'm dubious about the benefits of keeping nude photos of yourself. Second, and more importantly, because I don't think the risk is small.
The OP claims, "a vanishly small proportion of [nude photos] get stolen in security breaches of cloud storage," but I would wonder if we have any data on that. Maybe it happens all the time, but we just don't hear about it because the victims aren't celebrities. Not being a celebrity means both: (a) even if the photos were stolen, there's a much smaller chance that the victim would ever find out; and (b) even if the photos were stolen and the victim found out, there's a much smaller chance the general public would ever hear about it. The OP even acknowledges, "usually the far greater risk is that the recipient will forward the image to other people until it gets out of control," which essentially has the same effect. So even if you aren't concerned about cloud breaches, you should still be concerned about the photos being seen by people other than the intended recipients. (Actually, this is an important issue, since we don't know that all of the leaked photos came from a security breach, and some of them may have been leaked by the recipient forwarding the image to others).
But aside from all that, there's still another problem with this argument: even in cases where people have done a risk/benefit analysis and determined that there's a low risk, we still don't exempt people from the responsibility of that risk. Imagine that I invest all my money in a company that is, by all accounts, a safe investment. After some period of time, that company fails and I lose my investment. That stinks. I calculated my risk, and had no way of knowing that my investment was going to have bad results. It may be true that no one would blame me, but that doesn't mean that I can expect to get my money back. Someone might reasonably say to me, "That's bad luck, but you knew there was a risk when you bought the stock. It was a small risk, but a risk none the less, and you took that risk knowingly."
All in all, I think we need to stop trying to figure out blame, and figure out how to proceed. My advice to anyone out there is, if you can't handle the risk of someone seeing your nude photos, then don't take nude photos. Certainly don't store them online.