Where I think it would be reasonable to make changes is to carve out exceptions to these agreements that are always allowed. Sexual harassment, for example, shouldn't get to hide behind a signature that was made to receive severance. Likewise, it should always be allowed to report a crime to police, even if it means accusing a former employer. Making these carve-outs explicit might make these agreements more reasonable without limiting their attractiveness to companies offering severance.
Otherwise id be thinking well if they want me to sign this they must have done something wrong in the redundancy process
I could see agreements not to spout off opinions making sense, but having actual facts (or things you reasonably believe to be facts) ought to make it ok.
Rather like what the Internet tells me the difference between US and UK defamation laws is; if you have actual facts on your side you're ok, but if you're just expressing opinions then it depends (on where you are; or I'd like to think on what agreements you have).
I'm not a lawyer, I'm not your lawyer. If you need legal advice or need to make a defamatory statement get real legal advice.
Unfortunately, as soon as you use the o-word, you've lost probably 90% of your audience of self-sufficient bootstrappy meritocratic engineers, to whom the idea of collectively bargaining for anything with other employees is unacceptable. Unionization is such a bizarrely taboo topic among techies.
In the short term, it would be good if people could organize legal aid for people in our field working under nondisparagement clauses. Some of these clauses may be prima facie difficult to enforce due to language; others may leave room to report companies to legal authorities.
Finally, and I'm a broken record on this: if a significant fraction of engineers at any company organized themselves and demanded reasonable limitations on their nondisparagement clauses, for instance to protect whistleblowing, they would get it. What's a significant fraction? At many companies, it's probably less than 20%.
I hope a lot of tech industry employees are, as we speak, talking with their friendly peers at their companies and starting to think about how to reach out to labor lawyers to start this process. It's not that hard, and, for the time being, federal law protects you extensively in the process of organizing your workplace.