In this case it's a minor thing which probably wouldn't require much maintainance, but you have to draw the line somewhere.
If option for backspace behaviour suddenly starts interfering with some unrelated feature, it means somebody seriously fucked up the architecture of the project. Nothing else. Configuration flags aren't scary, and should not be used as a rationalization for dumbing down software.
In this case, the right thing really is contextual, so a configuration or extant setting / default is worth the cost in complexity.
The quote "Everything should be made as simple as possible, but not simpler" comes to mind here.
From the maintainer's point-of-view, having the option to bind "backspace" to "window.history.back" shouldn't require any more maintenance than having the option to bind "alt-left" to "window.history.back" does.
It is Google's fault that they didn't make Chrome work this way. It also means I can't unbind "ctrl-shift-q" from "quit_immediately_without_asking", because Google refuse to add an option to make it so that I can't accidentally fat-finger a C-w into something that ends my entire session. All keyboard shortcut problems disappear instantly if key bindings are configurable, however, without adding new options for each command.
This is a shortcut button … The maintenance argument is really a straw-man in this case …
> but you have to draw the line somewhere.
And this shows that they chose to place this line at «this product is our product, there is no customization options»
That said, I'm glad they finally did something to fix this bad UX design.
leaving it enabled also allows them to do this, which they have done for the last couple years and clearly their data says that it's not worth supporting, because now they're dropping it.