Are x11 bitmapped fonts necessary?

Solution 1:

The X server requires exactly two fonts, fixed and cursor, both of which are builtin to all recent versions of the libXfont library it uses.

Many older X applications however, may have specified those fonts - generally they'll fallback to using a default like fixed, but that may be missing some characters, and will probably be at a different size, thus leading to a different (sometimes broken) layout of menus, buttons, and other widgets spaced for the expected font/size.

Solution 2:

All modern GTK+ applications use Xft for font rendering. Xorg bitmap fonts are installed by default just for the sake of backward compatibility. In other words you can safely uninstall them if you don't use any legacy applications (eg. gitk).