But using the title bar is what most of us are used to.

Discoverability rears its head. I don't see how moving that functionality into some obscure button combination is better than obvious behavior.

I'm not advocating for this to become the default functionality across the world for everyone, it's definitely very opt-in.

In that case you don't need discoverability for something you set up yourself.

It's also very fun to play with when using the Wobbly Windows effect, you can stretch them in different ways depending on where exactly you picked the window up from.

I have Alt-LMB for moving, but that all falls to pot when I remote into another machine -- alt-lmb moves my rdp/vnc/browser, not the one in the screen I'm connected to.

Title bars also serve to more quickly recognize where windows are. If every application fills up the title bar with different stuff, it becomes harder to “parse” where windows are on the screen. There is an inherent benefit in windows having uniform “chrome”.