This. Configuration flags increase complexity. Every time you change the feature in question (or add something that uses it) you will have to take into account every possible flag combination.
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.