> I have to use Gmail in static HTML mode so that it doesn't try to reinvent and fail at a text edit control for composing a mail.
I'm not really sure what you are referring to here. Gmail does attempt to give you an editor for emails, but it's extremely simple in my experience to get it to do what you want most the time. If your complaint is that you want it to just send a text email, and not a multi-part with a plain text version and an HTML version, in which case I have to question why, as all it does it add choice and allow people to view it in the format they prefer, and it should look the same either way.
> grabbing more key bindings that existed before in a web browser like Ctrl-K and their comment edit box got limited in its resizability
Re: key binding, yeah, I can see that as somewhat annoying. I suspect they are trying to match some standard usability map and thinking of their site as an application, but it's annoying that it interferes with the browser (but only when within a text input, from what I can tell).
To some degree, I have to agree with what's probably Github's stance, which is that it's their site, and while it may seem annoying in some respects, they may have specific reasons they do things. They obviously aren't going to be able to make every change something everyone likes, but I don't necessarily think they are making change for change's sake. It's likely in response to pressure from gitlab and competitors. Presumably they are audience testing. The best way you can speak to this is to not use them when possible, or urge others to not use them.