The reason you aren't getting any feedback from GNOME developers is because this is a huge long rant without any real new information in it. The developers are already aware of what bugs are present and what features are missing. If it was easy to fix all the bugs and replace the extension system, they would have done it already. If you don't like GNOME's design then just don't use it, it's not possible to change the entire design of the whole system every time one person has a problem with it.
There won't be any official theming where they support changing application themes to whatever you want. That is and will always be a nasty hack -- the entire idea is flawed and conflicts with the idea of GNOME, which is to have a complete platform with a consistent look and behavior. It's impossible to have that and also have full theming capability at the same time, those two ideas are the opposite. IMO you should give up on that or you will be more disappointed in the future. At one time I too used to think it was possible but I gave it up when I realized it just isn't technically feasible.
There won't be any official theming where they support changing application themes to whatever you want. That is and will always be a nasty hack -- the entire idea is flawed and conflicts with the idea of GNOME, which is to have a complete platform with a consistent look and behavior. It's impossible to have that and also have full theming capability at the same time, those two ideas are the opposite. IMO you should give up on that or you will be more disappointed in the future. At one time I too used to think it was possible but I gave it up when I realized it just isn't technically feasible.