It's not just the Democrats going through this now. The Republican Party wants its chosen candidates and they get Trump and Cruz instead. Both parties are having to fight popular sentiment to get their candidates in the general election.
Except that the Republican "chosen candidate" (Jeb Bush)* is already out of the running, while it seems likely that the Democrat's "chosen candidate" will win the nomination, even if she loses the primaries.
*It looks like the Republican establishment has chosen Rubio as its fallback candidate.
The classic solution to the problem would be to establish a market in privacy because it is the most efficient known mechanism for allocating valuable items. If one could know the true costs and benefits of keeping a secret then most rational consumers would choose the level of privacy that suits them. However, this runs counter to the basic instincts of bureaucracy. For example, the European high court has decided to give a relatively obscure bureaucrat in Paris to the mandate "to lead an increasingly powerful group of European privacy regulators" to decide who gets access to what.
Power corrupts. And atomic power corrupts atomically.