What I do want to put the focus on, however, is that you have to perform an audit of your product every so often and see how the people using your product have changed, and what kind of functionality that made sense at the time may not make much sense anymore.

• load images automatically
• enable JS
• turn-off the navigation toolbar
• turning off SSL & TLS
• certificate manager
• override automatic cache management

The people that need to do these things should use add-ons, or at the very least an about:config tweak.

I would argue: it makes the configuration or preferences UI lightweight.