If you wish to create such a patch with those optional components using "--enable-feature" I'd be willing to look it over and integrate them. As Philippe pointed out cairo and libpng are still required for tty usage where one is supporting exports. I do agree with the assessment with sound and the without GTK option. If your not using GTK we probably shouldn't be using a dependency (canberra) that relies on it. Just a note that sound on Windows and OS/X do not rely on GTK as we use their native sound systems.

This is not entirely accurate. cairo is used in exports to ps or pdf, libpng in export position to png, features that make sense even with the tty interface only. On the other hand, canberra or sound libraries in general probably belong the the gui builds only.

I'd consider this report a reminder that there must be some clean-up or simplification to do in this area, but I don't think it is as straightforward as suggested.