I read a while back about a law firm that had evidently done something very dodgy - representing an inventor and the firm purchasing the invention at the same time. The engineers were eventually paid a settlement, but part of the settlement was a gag order - nobody was allowed to talk about what had happened or the amount of money paid. This included, of course, the press.
Now, what do you want to bet that well connected lawyers, upper managers, and so forth, are able to access the terms of this deal - even if they weren't involved? What are the odds that an inventor who approaches a law firm will know what transpired and why? The imbalance of information will put the inventor at an overwhelming disadvantage.
My gut feeling is that there is a third party in all of this - me. Well, me, and all the little people. I understand the need to enforce contracts within reason, but I'm having a tough time seeing my own personal interest, or the general public interest, in enforcing these "stay quiet" contracts.
I'd also point out that this isn't really a situation where we are prying into a private transaction and forcing people to talk. Our courts are actually enforcing the gag rule that keeps most of us in the dark about what is really going on out there. My misgivings about regulating private transactions aren't as strong when all we'd need to do is stop enforcing contracts that are clearly against the public interest [1].
[1] I am still thinking this through. I'm not absolutely sure this is against the public interest, or, even if it is, if we the courts should refuse to enforce the provision. It's how I'm leaning, but I have a sense that there may be more to this. I am generally glad that courts won't enforce certain terms of contracts, such as very long non-compete clauses and the like...