On Fri, 14 Nov 2014 16:16:56 -0800 (PST), RichA
wrote:

Practically nobody is opposed to using RTGs. But that doesn't make
them the technology of choice for every application. That would have
been a poor engineering decision in this case.

Why?

Because of mass constraints. Because of budget constraints. Because of
risk versus benefit analysis. These things are real. Every design is a
balance of engineering decisions.

Believe it or not, the scientists and engineers who design these
missions know what they're doing. Where is your source of information
to second guess them?