Yes, a nuclear blast is a lot more visible than an ongoing mass surveillance program. However, I would say that it is extremely hard to keep something like PRISM secret forever. Even if there is only a tiny probability of the information leaking each year, over the years the chance of keeping it secret decreases geometrically. All it takes is one upload to wikileaks.
I agree that more transparency is a good idea. In fact, I think more transparency and less funding is a good idea for the intelligence agencies in general. We're living in a comparative time of peace, which means the incentives for these agencies (and the closely related private contractors) are to inflate their budgets and create work for themselves. Currently this seems to be driving an obsessive mission to monitor everything and everyone. This is bad enough of itself, but it could easily turn into creating enemies where none exist.
I agree that more transparency is a good idea. In fact, I think more transparency and less funding is a good idea for the intelligence agencies in general. We're living in a comparative time of peace, which means the incentives for these agencies (and the closely related private contractors) are to inflate their budgets and create work for themselves. Currently this seems to be driving an obsessive mission to monitor everything and everyone. This is bad enough of itself, but it could easily turn into creating enemies where none exist.