>I generally agree with JMK, but I think that "I am sure that the power of vested interests is vastly exaggerated compared with the gradual encroachment of ideas." underestimates the power of vested interests.

He does. Specially now that...

>While it's true that over a long period, people ultimately do the "reasonable" thing look at how long powerful institutions like the divine right of kings and slave owning held sway.
>For a more contemporary example, consider the enormous monopolistic power that the broadcast and cable industries have seized over broadcast frequencies which are, after all, a public asset

...they have ways to influence the world of ideas, insert their own, pay their own theoreticians to take the discussion into irrelevant fields etc etc.

And by the time the people decide to do the reasonable thing about some issue, they have opened sixty other issues. The issues fixed that way are mostly those that the interests don't find in their interest to keep.