From siblings to my comment:
You can't tell them: They can only learn this through experience. Alternately they may be the sort of shop where average developers are perfectly satisfactory.
read: The counter-party to your negotiation is not an honest/competent partner who may have reached a rational conclusion given their understanding of the situation. Also, exceptional talent doesn't need to be treated like this. Conclusion: only average talent negotiates, compromises, respects management's motives. Exceptional talent finds a different party.
You don't tell somebody such a thing. It would never work. The rules are the rules to most people... It's not always better to have "great" engineers - often companies just want somebody sitting at their desk ready to act on instructions. If that's the case then there is probably a lower-skilled engineer that would count themselves lucky to be sitting at a desk for 8 hours. He will be a lot easier to manage and probably a lot more appropriate for the new management.
read: Management is hidebound and petty. No possibility for compromise exists. Management placing burdensome demands on your time, therefore, is not an opportunity to negotiate but a cause to leave. Tolerance of such a situation is for low-skill employees only.
It's called an exit interview. Once you secure a new job, don't be shy with your managers about why you are leaving.
read: Don't try to constructively engage your management. Exercise your opportunity to leave, and then, once your exit is secure, air your displeasure with policy changes.
You don't need to tell them anything. If you're a good developer, you choose where and with whom to work. Feel your power and use your power.
read: Obviously management has no legitimate concern here, or interest in expressing how employee time is structured.
You quit.
By not continuing to work under managers that are shitty.
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I could go on. I may have miscounted on the ratio, but it's hardly "none-to-one"