I think we have removed all the FA calls from 1.1, updating them all with SVG images so there should be no need to load it by default.
In 1.0 the FA css is always loaded by the core since we use it in the default theme. I'm thinking we can update that to only load if a) the theme settings calls for it, or b) a modification calls for it. Also depreciate it so it can be removed in 2.0.
Something like
if (!empty($settings['require_font-awesome']) || !empty($modSettings['require_font-awesome']))
loadCSSFile('font-awesome.min.css');
Any objections?