'm pretty sure (prior to 2 weeks ago anyway) that if any of our top 20 didn't respond when new code was put forward, they would be out in a matter of days

That's just not correct. There are numerous cases (at least two I can think of immediately) on Steem where witnesses have refused to update to new code that was put forward and were not out in a matter of days.

The developers don't get to unilatearlly jam whatever code they want down the community's and witness's throats, except on a centralized sham of a chain like Tron.

The way the system works is that witnesses opposed to an update have the prerogative to not adopt it. It is then up to those who want it adopted to convince those against and/or make changes to address the concerns and attract broader support for it.

I'm no Ned fan but to his credit, apart from one exception, he actually respected this aspect of the system enough to refrain from using the Steemit stake to centralize the chain. Justin, on the other hand, appears to repeatedly show himself to be someone who wants to be a dictator, using any means he can to get his way regardless of what anyone else thinks.